feat(treewide): Add tests and barcode buying/consuming

33 files changed, 1320 insertions, 58 deletions

diff --git a/crates/rocie-cli/Cargo.toml b/crates/rocie-cli/Cargo.toml
index e68a7b4..5e878fd 100644
--- a/crates/rocie-cli/Cargo.toml
+++ b/crates/rocie-cli/Cargo.toml
@@ -30,7 +30,7 @@ workspace = true
 anyhow = "1.0.99"
 clap = { version = "4.5.47", features = ["derive"] }
 rocie-client.workspace = true
-tokio = { version = "1.47.1", features = ["macros", "rt-multi-thread"] }
+tokio.workspace = true
 uuid = "1.18.1"
 
 
diff --git a/crates/rocie-cli/src/cli.rs b/crates/rocie-cli/src/cli.rs
index 3f2662b..29c284f 100644
--- a/crates/rocie-cli/src/cli.rs
+++ b/crates/rocie-cli/src/cli.rs
@@ -20,6 +20,12 @@ pub(crate) enum Command {
         #[command(subcommand)]
         command: UnitCommand,
     },
+
+    /// Deal with Barcodes
+    Barcode {
+        #[command(subcommand)]
+        command: BarcodeCommand,
+    },
 }
 
 #[derive(Subcommand)]
@@ -58,6 +64,32 @@ pub(crate) enum UnitCommand {
 }
 
 #[derive(Subcommand)]
+#[expect(variant_size_differences, reason = "It's just a testing cli")]
+pub(crate) enum BarcodeCommand {
+    /// Buy an barcode
+    Buy {
+        /// The numeric value of the barcode
+        #[arg(short, long)]
+        id: u32,
+    },
+
+    /// Consume an barcode
+    Consume {
+        /// The numeric value of the barcode
+        #[arg(short, long)]
+        id: u32,
+
+        /// The amount to consume
+        #[arg(short, long)]
+        amount: u32,
+
+        /// The unit of the consumed amount
+        #[arg(short, long)]
+        unit_id: Uuid,
+    },
+}
+
+#[derive(Subcommand)]
 pub(crate) enum ProductCommand {
     /// Register a new product
     Register {
diff --git a/crates/rocie-cli/src/handle/mod.rs b/crates/rocie-cli/src/handle/mod.rs
index 1d322f8..c39f7b1 100644
--- a/crates/rocie-cli/src/handle/mod.rs
+++ b/crates/rocie-cli/src/handle/mod.rs
@@ -1,10 +1,12 @@
-use crate::cli::{ProductCommand, UnitCommand};
+use crate::cli::{BarcodeCommand, ProductCommand, UnitCommand};
 
 use anyhow::{Context, Result};
 use rocie_client::{
     apis::{
+        api_get_inventory_api::amount_by_id,
         api_get_product_api::{product_by_id, products},
         api_get_unit_api::{unit_by_id, units},
+        api_set_barcode_api::{buy_barcode, consume_barcode},
         api_set_product_api::{associate_barcode, register_product},
         api_set_unit_api::register_unit,
         configuration::Configuration,
@@ -46,19 +48,29 @@ pub(crate) async fn product(config: &Configuration, command: ProductCommand) ->
             barcode_number,
             amount_value,
             amount_unit_id,
-        } => associate_barcode(
-            config,
-            product_id.to_string().as_str(),
-            Barcode {
-                id: i64::from(barcode_number),
-                amount: Box::new(UnitAmount {
-                    unit: amount_unit_id,
-                    value: i64::from(amount_value),
-                }),
-            },
-        )
-        .await
-        .context("Failed to associated barcode")?,
+        } => {
+            associate_barcode(
+                config,
+                product_id.to_string().as_str(),
+                Barcode {
+                    id: i32::try_from(barcode_number).unwrap(),
+                    amount: Box::new(UnitAmount {
+                        unit: amount_unit_id,
+                        value: i64::from(amount_value),
+                    }),
+                },
+            )
+            .await
+            .context("Failed to associated barcode")?;
+
+            let unit = unit_by_id(config, amount_unit_id.to_string().as_str()).await?;
+            let product = product_by_id(config, product_id.to_string().as_str()).await?;
+
+            println!(
+                "Associated barcode ({barcode_number} - {amount_value} {}) with product: {} ",
+                unit.short_name, product.name
+            );
+        }
 
         ProductCommand::List {} => {
             let all = products(config)
@@ -68,6 +80,19 @@ pub(crate) async fn product(config: &Configuration, command: ProductCommand) ->
             for product in all {
                 print!("{}: {}", product.name, product.id);
 
+                {
+                    let product_amount = amount_by_id(config, product.id.to_string().as_str())
+                        .await
+                        .with_context(|| {
+                            format!("Failed to get amount of product: {}", product.id)
+                        })?;
+
+                    let unit =
+                        unit_by_id(config, product_amount.amount.unit.to_string().as_str()).await?;
+
+                    print!(" available: {} {}", product_amount.amount.value, unit.short_name);
+                }
+
                 if let Some(description) = product
                     .description
                     .expect("Superflous Option wrapping in api")
@@ -77,11 +102,15 @@ pub(crate) async fn product(config: &Configuration, command: ProductCommand) ->
                     println!();
                 }
 
+                if !product.associated_bar_codes.is_empty() {
+                    println!("  Barcodes:");
+                }
+
                 for barcode in product.associated_bar_codes {
                     let unit = unit_by_id(config, barcode.amount.unit.to_string().as_str()).await?;
 
                     println!(
-                        "  - {}: {} {}",
+                        "    - {}: {} {}",
                         barcode.id,
                         barcode.amount.value,
                         if barcode.amount.value == 1 {
@@ -97,6 +126,31 @@ pub(crate) async fn product(config: &Configuration, command: ProductCommand) ->
     Ok(())
 }
 
+pub(crate) async fn barcode(config: &Configuration, command: BarcodeCommand) -> Result<()> {
+    match command {
+        BarcodeCommand::Buy { id } => {
+            buy_barcode(config, i32::try_from(id).unwrap()).await?;
+        }
+        BarcodeCommand::Consume {
+            id,
+            amount,
+            unit_id,
+        } => {
+            consume_barcode(
+                config,
+                i32::try_from(id).unwrap(),
+                UnitAmount {
+                    unit: unit_id,
+                    value: i64::from(amount),
+                },
+            )
+            .await?;
+        }
+    }
+
+    Ok(())
+}
+
 pub(crate) async fn unit(config: &Configuration, command: UnitCommand) -> Result<()> {
     match command {
         UnitCommand::Register {
diff --git a/crates/rocie-cli/src/main.rs b/crates/rocie-cli/src/main.rs
index ef81ad9..e3188c8 100644
--- a/crates/rocie-cli/src/main.rs
+++ b/crates/rocie-cli/src/main.rs
@@ -17,6 +17,7 @@ async fn main() -> Result<()> {
     match args.command {
         Command::Product { command } => handle::product(&config, command).await?,
         Command::Unit { command } => handle::unit(&config, command).await?,
+        Command::Barcode { command } => handle::barcode(&config, command).await?,
     }
 
     Ok(())
diff --git a/crates/rocie-server/Cargo.toml b/crates/rocie-server/Cargo.toml
index 93dbcd4..2ea5f3d 100644
--- a/crates/rocie-server/Cargo.toml
+++ b/crates/rocie-server/Cargo.toml
@@ -27,11 +27,13 @@ publish = false
 workspace = true
 
 [dev-dependencies]
+rocie-client.workspace = true
+tokio.workspace = true
 
 [dependencies]
 actix-web = "4.11.0"
 chrono = "0.4.41"
-clap = { version = "4.5.45", features = ["derive"] }
+clap = { version = "4.5.45", features = ["derive", "env"] }
 env_logger = "0.11.8"
 log = "0.4.27"
 serde = { version = "1.0.219", features = ["derive"] }
diff --git a/crates/rocie-server/src/api/get/inventory.rs b/crates/rocie-server/src/api/get/inventory.rs
new file mode 100644
index 0000000..3011430
--- /dev/null
+++ b/crates/rocie-server/src/api/get/inventory.rs
@@ -0,0 +1,44 @@
+use actix_web::{HttpResponse, Responder, Result, get, web};
+
+use crate::{
+    app::App,
+    storage::sql::{product::ProductId, product_amount::ProductAmount},
+};
+
+/// Get the amount of an product
+#[utoipa::path(
+    responses(
+        (
+            status = OK,
+            description = "Product found in database and amount fetched",
+            body = ProductAmount
+        ),
+        (
+            status = NOT_FOUND,
+            description = "Product not found in database"
+        ),
+        (
+            status = INTERNAL_SERVER_ERROR,
+            description = "Server encountered error",
+            body = String
+        )
+    ),
+    params(
+        (
+            "id" = ProductId,
+            description = "Product id"
+        ),
+    )
+)]
+#[get("/inventory/{id}")]
+pub(crate) async fn amount_by_id(
+    app: web::Data<App>,
+    id: web::Path<ProductId>,
+) -> Result<impl Responder> {
+    let id = id.into_inner();
+
+    match ProductAmount::from_id(&app, id).await? {
+        Some(product) => Ok(HttpResponse::Ok().json(product)),
+        None => Ok(HttpResponse::NotFound().finish()),
+    }
+}
diff --git a/crates/rocie-server/src/api/get/mod.rs b/crates/rocie-server/src/api/get/mod.rs
index ce39076..21684af 100644
--- a/crates/rocie-server/src/api/get/mod.rs
+++ b/crates/rocie-server/src/api/get/mod.rs
@@ -1,5 +1,6 @@
 use actix_web::web;
 
+pub(crate) mod inventory;
 pub(crate) mod product;
 pub(crate) mod unit;
 
@@ -7,5 +8,6 @@ pub(crate) fn register_paths(cfg: &mut web::ServiceConfig) {
     cfg.service(product::product_by_id)
         .service(product::products)
         .service(unit::units)
-        .service(unit::unit_by_id);
+        .service(unit::unit_by_id)
+        .service(inventory::amount_by_id);
 }
diff --git a/crates/rocie-server/src/api/set/barcode.rs b/crates/rocie-server/src/api/set/barcode.rs
new file mode 100644
index 0000000..a89bf4f
--- /dev/null
+++ b/crates/rocie-server/src/api/set/barcode.rs
@@ -0,0 +1,97 @@
+use actix_web::{HttpResponse, Responder, Result, post, web};
+use log::debug;
+
+use crate::{
+    app::App,
+    storage::sql::{
+        barcode::{Barcode, BarcodeId, UnitAmount},
+        insert::Operations,
+    },
+};
+
+/// Buy an barcode
+#[utoipa::path(
+    responses(
+        (
+            status = OK,
+            description = "Barcode successfully bought",
+        ),
+        (
+            status = NOT_FOUND,
+            description = "Barcode id was not found",
+        ),
+        (
+            status = INTERNAL_SERVER_ERROR,
+            description = "Server encountered error",
+            body = String,
+        )
+    ),
+    params(
+        ("id" = BarcodeId, description = "The numeric value of the barcode"),
+    )
+)]
+#[post("/barcode/{id}/buy")]
+pub(crate) async fn buy_barcode(
+    app: web::Data<App>,
+    barcode_id: web::Path<BarcodeId>,
+) -> Result<impl Responder> {
+    let mut ops = Operations::new("buy barcode unit");
+
+    let barcode = Barcode::from_id(&app, barcode_id.into_inner()).await?;
+
+    match barcode {
+        Some(barcode) => {
+            barcode.buy(&mut ops);
+
+            ops.apply(&app).await?;
+
+            Ok(HttpResponse::Ok().finish())
+        }
+        None => Ok(HttpResponse::NotFound().finish()),
+    }
+}
+
+/// Consume an barcode
+#[utoipa::path(
+    responses(
+        (
+            status = OK,
+            description = "Barcode successfully consumed",
+        ),
+        (
+            status = NOT_FOUND,
+            description = "Barcode id was not found",
+        ),
+        (
+            status = INTERNAL_SERVER_ERROR,
+            description = "Server encountered error",
+            body = String,
+        )
+    ),
+    params(
+        ("id" = BarcodeId, description = "The numeric value of the barcode"),
+    ),
+    request_body = UnitAmount,
+)]
+#[post("/barcode/{id}/consume")]
+pub(crate) async fn consume_barcode(
+    app: web::Data<App>,
+    barcode_id: web::Path<BarcodeId>,
+    unit_amount: web::Json<UnitAmount>,
+) -> Result<impl Responder> {
+    let mut ops = Operations::new("consume barcode unit");
+
+    let barcode = Barcode::from_id(&app, barcode_id.into_inner()).await?;
+    debug!("Starting consume for barcode: {barcode:?}");
+
+    match barcode {
+        Some(barcode) => {
+            barcode.consume(&app, unit_amount.into_inner(), &mut ops).await?;
+
+            ops.apply(&app).await?;
+
+            Ok(HttpResponse::Ok().finish())
+        }
+        None => Ok(HttpResponse::NotFound().finish()),
+    }
+}
diff --git a/crates/rocie-server/src/api/set/mod.rs b/crates/rocie-server/src/api/set/mod.rs
index 8a2a1df..a7ddab5 100644
--- a/crates/rocie-server/src/api/set/mod.rs
+++ b/crates/rocie-server/src/api/set/mod.rs
@@ -1,10 +1,13 @@
 use actix_web::web;
 
+pub(crate) mod barcode;
 pub(crate) mod product;
 pub(crate) mod unit;
 
 pub(crate) fn register_paths(cfg: &mut web::ServiceConfig) {
     cfg.service(product::register_product)
         .service(product::associate_barcode)
-        .service(unit::register_unit);
+        .service(unit::register_unit)
+        .service(barcode::consume_barcode)
+        .service(barcode::buy_barcode);
 }
diff --git a/crates/rocie-server/src/api/set/product.rs b/crates/rocie-server/src/api/set/product.rs
index 355f09a..19024c7 100644
--- a/crates/rocie-server/src/api/set/product.rs
+++ b/crates/rocie-server/src/api/set/product.rs
@@ -5,8 +5,9 @@ use utoipa::ToSchema;
 use crate::{
     app::App,
     storage::sql::{
+        barcode::Barcode,
         insert::Operations,
-        product::{Barcode, Product, ProductId},
+        product::{Product, ProductId},
         unit::Unit,
     },
 };
diff --git a/crates/rocie-server/src/app.rs b/crates/rocie-server/src/app.rs
index ab8f764..bb27470 100644
--- a/crates/rocie-server/src/app.rs
+++ b/crates/rocie-server/src/app.rs
@@ -1,4 +1,4 @@
-use std::{env, path::PathBuf};
+use std::path::PathBuf;
 
 use sqlx::{SqlitePool, sqlite::SqliteConnectOptions};
 
@@ -10,9 +10,7 @@ pub(crate) struct App {
 }
 
 impl App {
-    pub(crate) async fn new() -> Result<Self, app_create::Error> {
-        let db_path: PathBuf = PathBuf::from(env::var("ROCIE_DB_PATH")?);
-
+    pub(crate) async fn new(db_path: PathBuf) -> Result<Self, app_create::Error> {
         let db = {
             let options = SqliteConnectOptions::new()
                 .filename(&db_path)
@@ -36,15 +34,12 @@ impl App {
 }
 
 pub(crate) mod app_create {
-    use std::{env, path::PathBuf};
+    use std::path::PathBuf;
 
     use crate::storage::migrate::migrate_db;
 
     #[derive(thiserror::Error, Debug)]
     pub(crate) enum Error {
-        #[error("The `ROCIE_DB_PATH` variable is not accessible: {0}")]
-        MissingDbVariable(#[from] env::VarError),
-
         #[error("Failed to connect to the sqlite database at `{db_path}`, because: {inner}")]
         DbConnectionFailed {
             inner: sqlx::Error,
diff --git a/crates/rocie-server/src/cli.rs b/crates/rocie-server/src/cli.rs
index 5961ab7..b2ec214 100644
--- a/crates/rocie-server/src/cli.rs
+++ b/crates/rocie-server/src/cli.rs
@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 use clap::{Parser, Subcommand};
 
 #[derive(Parser)]
@@ -8,8 +10,20 @@ pub(crate) struct CliArgs {
 
 #[derive(Subcommand)]
 pub(crate) enum Command {
-    /// Serve the server on the default ports.
-    Serve,
+    /// Serve the server.
+    Serve {
+        /// Which port to serve the server on.
+        #[arg(short, long, default_value = "8080")]
+        port: u16,
+
+        /// Which host to serve the server on.
+        #[arg(short = 'b', long, default_value = "127.0.0.1")]
+        host: String,
+
+        /// Path to the database to use to store data.
+        #[arg(short, long, env = "ROCIE_DB_PATH")]
+        db_path: PathBuf,
+    },
 
     /// Print the `OpenAPI` API documentation to stdout.
     OpenApi,
diff --git a/crates/rocie-server/src/main.rs b/crates/rocie-server/src/main.rs
index c896c35..8e71034 100644
--- a/crates/rocie-server/src/main.rs
+++ b/crates/rocie-server/src/main.rs
@@ -22,9 +22,12 @@ async fn main() -> Result<(), std::io::Error> {
             api::get::product::products,
             api::get::unit::units,
             api::get::unit::unit_by_id,
+            api::get::inventory::amount_by_id,
             api::set::product::register_product,
             api::set::product::associate_barcode,
             api::set::unit::register_unit,
+            api::set::barcode::buy_barcode,
+            api::set::barcode::consume_barcode,
         ),
     // security(
     //     (),
@@ -39,11 +42,13 @@ async fn main() -> Result<(), std::io::Error> {
     let args = CliArgs::parse();
 
     match args.command {
-        Command::Serve => {
-            let host = "127.0.0.1";
-            let port = 8080;
+        Command::Serve {
+            host,
+            port,
+            db_path,
+        } => {
             let data = Data::new(
-                app::App::new()
+                app::App::new(db_path)
                     .await
                     .map_err(|err| std::io::Error::other(main::Error::AppInit(err)))?,
             );
@@ -52,7 +57,9 @@ async fn main() -> Result<(), std::io::Error> {
 
             HttpServer::new(move || {
                 App::new()
-                    .wrap(Logger::new(r#"%a "%r" -> %s %b ("%{Referer}i" "%{User-Agent}i" %T s)"#))
+                    .wrap(Logger::new(
+                        r#"%a "%r" -> %s %b ("%{Referer}i" "%{User-Agent}i" %T s)"#,
+                    ))
                     .app_data(Data::clone(&data))
                     .configure(api::get::register_paths)
                     .configure(api::set::register_paths)
diff --git a/crates/rocie-server/src/storage/migrate/mod.rs b/crates/rocie-server/src/storage/migrate/mod.rs
index 3fdc400..ae0732b 100644
--- a/crates/rocie-server/src/storage/migrate/mod.rs
+++ b/crates/rocie-server/src/storage/migrate/mod.rs
@@ -198,7 +198,7 @@ pub(crate) mod db_version_parse {
 }
 
 /// Returns the current data as UNIX time stamp.
-fn get_current_date() -> i64 {
+pub(crate) fn get_current_date() -> i64 {
     let start = SystemTime::now();
     let seconds_since_epoch: TimeDelta = TimeDelta::from_std(
         start
diff --git a/crates/rocie-server/src/storage/migrate/sql/0->1.sql b/crates/rocie-server/src/storage/migrate/sql/0->1.sql
index 5aa497d..fd48c68 100644
--- a/crates/rocie-server/src/storage/migrate/sql/0->1.sql
+++ b/crates/rocie-server/src/storage/migrate/sql/0->1.sql
@@ -19,13 +19,45 @@ CREATE TABLE version (
 -- TODO: Fix the possibility for cyclic parent-ship entries <2025-09-05>
 CREATE TABLE parents (
     id                          TEXT UNIQUE NOT NULL PRIMARY KEY,
-    parent                      TEXT                             DEFAULT NULL CHECK (id IS NOT parent),
+    parent                      TEXT                             DEFAULT NULL CHECK (
+                                                                            id IS NOT parent
+                                                                        ),
     FOREIGN KEY(parent) REFERENCES parents(id)
 ) STRICT;
 
+-- Record with barcodes were bought, and how much of this buy is already used up.
+CREATE TABLE buys (
+    buy_id              TEXT    UNIQUE NOT NULL PRIMARY KEY,
+    barcode_id          INTEGER        NOT NULL,
+    used_amount         INTEGER                              DEFAULT NULL CHECK (used_amount > 0),
+    timestamp           INTEGER        NOT NULL,
+    FOREIGN KEY(barcode_id) REFERENCES barcodes(id)
+) STRICT;
+
+CREATE TRIGGER used_amount_lower_or_equal_than_actual_amount_update
+BEFORE UPDATE OF used_amount ON buys
+FOR EACH ROW
+BEGIN
+    SELECT RAISE(FAIL, "Used amount higher than actual amount")
+    FROM barcodes
+    WHERE NEW.barcode_id = barcodes.id
+      AND NEW.used_amount > barcodes.amount;
+END;
+
+CREATE TRIGGER used_amount_lower_or_equal_than_actual_amount_insert
+BEFORE INSERT ON buys
+FOR EACH ROW
+BEGIN
+    SELECT RAISE(FAIL, "Used amount higher than actual amount")
+    FROM barcodes
+    WHERE NEW.barcode_id = barcodes.id
+      AND NEW.used_amount > barcodes.amount;
+END;
+
+
 CREATE TABLE products (
     id                          TEXT UNIQUE NOT NULL PRIMARY KEY,
-    name                        TEXT           NOT NULL,
+    name                        TEXT        NOT NULL,
     description                 TEXT,
     parent                      TEXT                             DEFAULT NULL,
     FOREIGN KEY(parent) REFERENCES parents(id)
diff --git a/crates/rocie-server/src/storage/sql/barcode.rs b/crates/rocie-server/src/storage/sql/barcode.rs
new file mode 100644
index 0000000..239ed8c
--- /dev/null
+++ b/crates/rocie-server/src/storage/sql/barcode.rs
@@ -0,0 +1,30 @@
+use serde::{Deserialize, Serialize};
+use utoipa::ToSchema;
+
+use crate::storage::sql::unit::UnitId;
+
+#[derive(ToSchema, Debug, Clone, Serialize, Deserialize)]
+pub(crate) struct Barcode {
+    #[schema(format = Int64, minimum = 0)]
+    pub(crate) id: BarcodeId,
+    pub(crate) amount: UnitAmount,
+}
+
+#[derive(ToSchema, Debug, Clone, Copy, Serialize, Deserialize)]
+pub(crate) struct BarcodeId(u32);
+
+impl BarcodeId {
+    pub(crate) fn to_db(self) -> i64 {
+        i64::from(self.0)
+    }
+    pub(crate) fn from_db(val: i64) -> Self {
+        Self(u32::try_from(val).expect("Should be strictly positive"))
+    }
+}
+
+#[derive(ToSchema, Debug, Clone, Copy, Serialize, Deserialize)]
+pub(crate) struct UnitAmount {
+    #[schema(format = Int64, minimum = 0)]
+    pub(crate) value: u32,
+    pub(crate) unit: UnitId,
+}
diff --git a/crates/rocie-server/src/storage/sql/get/barcode/mod.rs b/crates/rocie-server/src/storage/sql/get/barcode/mod.rs
new file mode 100644
index 0000000..7b656b1
--- /dev/null
+++ b/crates/rocie-server/src/storage/sql/get/barcode/mod.rs
@@ -0,0 +1,50 @@
+use crate::{
+    app::App,
+    storage::sql::{
+        barcode::{Barcode, BarcodeId, UnitAmount},
+        unit::UnitId,
+    },
+};
+
+use sqlx::query;
+
+impl Barcode {
+    pub(crate) async fn from_id(app: &App, id: BarcodeId) -> Result<Option<Self>, from_id::Error> {
+        let db_id = id.to_db();
+
+        let record = query!(
+            "
+        SELECT product_id, amount, unit
+        FROM barcodes
+        WHERE id = ?
+",
+            db_id
+        )
+        .fetch_optional(&app.db)
+        .await?;
+
+        if let Some(record) = record {
+            Ok(Some(Self {
+                id,
+                amount: UnitAmount {
+                    value: u32::try_from(record.amount).expect("Is strictly positive"),
+                    unit: UnitId::from_db(&record.unit),
+                },
+            }))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+pub(crate) mod from_id {
+    use actix_web::ResponseError;
+
+    #[derive(thiserror::Error, Debug)]
+    pub(crate) enum Error {
+        #[error("Failed to execute the sql query")]
+        SqlError(#[from] sqlx::Error),
+    }
+
+    impl ResponseError for Error {}
+}
diff --git a/crates/rocie-server/src/storage/sql/get/mod.rs b/crates/rocie-server/src/storage/sql/get/mod.rs
index fa22f81..048cb3d 100644
--- a/crates/rocie-server/src/storage/sql/get/mod.rs
+++ b/crates/rocie-server/src/storage/sql/get/mod.rs
@@ -1,2 +1,4 @@
 pub(crate) mod product;
+pub(crate) mod product_amount;
 pub(crate) mod unit;
+pub(crate) mod barcode;
diff --git a/crates/rocie-server/src/storage/sql/get/product/mod.rs b/crates/rocie-server/src/storage/sql/get/product/mod.rs
index d23297a..541f388 100644
--- a/crates/rocie-server/src/storage/sql/get/product/mod.rs
+++ b/crates/rocie-server/src/storage/sql/get/product/mod.rs
@@ -1,7 +1,8 @@
 use crate::{
     app::App,
     storage::sql::{
-        product::{Barcode, Product, ProductId, UnitAmount},
+        barcode::{Barcode, BarcodeId, UnitAmount},
+        product::{Product, ProductId},
         unit::UnitId,
     },
 };
@@ -63,7 +64,7 @@ impl Product {
                 associated_bar_codes: barcodes
                     .into_iter()
                     .map(|record| Barcode {
-                        id: u32::try_from(record.id).expect("Should be strictly positive"),
+                        id: BarcodeId::from_db(record.id),
                         amount: UnitAmount {
                             value: u32::try_from(record.amount)
                                 .expect("Should be strictly positve"),
diff --git a/crates/rocie-server/src/storage/sql/get/product_amount/mod.rs b/crates/rocie-server/src/storage/sql/get/product_amount/mod.rs
new file mode 100644
index 0000000..7700274
--- /dev/null
+++ b/crates/rocie-server/src/storage/sql/get/product_amount/mod.rs
@@ -0,0 +1,56 @@
+use crate::{
+    app::App,
+    storage::sql::{
+        barcode::UnitAmount, product::ProductId, product_amount::ProductAmount, unit::UnitId,
+    },
+};
+
+use sqlx::query;
+
+impl ProductAmount {
+    pub(crate) async fn from_id(
+        app: &App,
+        product_id: ProductId,
+    ) -> Result<Option<Self>, from_id::Error> {
+        let record = query!(
+            r#"
+SELECT
+    SUM(barcodes.amount - IFNULL(buys.used_amount,0)) "available_amount: u32",
+    barcodes.unit
+FROM barcodes
+    JOIN products ON products.id = ?
+    JOIN buys ON buys.barcode_id = barcodes.id
+GROUP BY barcodes.unit;
+"#,
+            product_id
+        )
+        .fetch_all(&app.db)
+        .await?;
+
+        assert!(record.len() <= 1, "We currently only support one unit");
+
+        if let Some(record) = record.first() {
+            Ok(Some(Self {
+                product_id,
+                amount: UnitAmount {
+                    value: record.available_amount.expect("Should always be set"),
+                    unit: UnitId::from_db(&record.unit),
+                },
+            }))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+pub(crate) mod from_id {
+    use actix_web::ResponseError;
+
+    #[derive(thiserror::Error, Debug)]
+    pub(crate) enum Error {
+        #[error("Failed to execute the sql query")]
+        SqlError(#[from] sqlx::Error),
+    }
+
+    impl ResponseError for Error {}
+}
diff --git a/crates/rocie-server/src/storage/sql/insert/barcode/mod.rs b/crates/rocie-server/src/storage/sql/insert/barcode/mod.rs
new file mode 100644
index 0000000..62a2e11
--- /dev/null
+++ b/crates/rocie-server/src/storage/sql/insert/barcode/mod.rs
@@ -0,0 +1,241 @@
+use std::str::FromStr;
+
+use serde::{Deserialize, Serialize};
+use sqlx::query;
+use uuid::Uuid;
+
+use crate::{
+    app::App,
+    storage::{
+        migrate::get_current_date,
+        sql::{
+            barcode::{Barcode, BarcodeId, UnitAmount},
+            insert::{Operations, Transactionable},
+            unit::Unit,
+        },
+    },
+};
+
+#[derive(Debug, Deserialize, Serialize)]
+pub(crate) enum Operation {
+    Buy {
+        buy_id: Uuid,
+        id: BarcodeId,
+    },
+    Consume {
+        buy_id: Uuid,
+        id: BarcodeId,
+        amount: UnitAmount,
+    },
+}
+
+impl Transactionable for Operation {
+    type ApplyError = apply::Error;
+    type UndoError = undo::Error;
+
+    async fn apply(self, txn: &mut sqlx::SqliteConnection) -> Result<(), apply::Error> {
+        match self {
+            Operation::Buy { buy_id, id } => {
+                let id = id.to_db();
+                let buy_id = buy_id.to_string();
+                let timestamp = get_current_date();
+
+                query!(
+                    "
+                    INSERT INTO buys (buy_id, barcode_id, timestamp)
+                    VALUES (?, ?, ?)
+",
+                    buy_id,
+                    id,
+                    timestamp,
+                )
+                .execute(txn)
+                .await?;
+            }
+            Operation::Consume { buy_id, id, amount } => {
+                let id = id.to_db();
+                let buy_id = buy_id.to_string();
+
+                let old_amount = {
+                    let record = query!(
+                        "
+                        SELECT used_amount
+                        FROM buys
+                        WHERE buy_id = ?;
+",
+                        buy_id
+                    )
+                    .fetch_one(&mut *txn)
+                    .await?;
+
+                    u32::try_from(record.used_amount.unwrap_or(0))
+                        .expect("Should be strictly positive")
+                };
+
+                // TODO: Check, that this does not overflow the maximum amount. <2025-09-21>
+                let new_amount = amount.value + old_amount;
+
+                // TODO(@bpeetz): We need to add the amount. <2025-09-09>
+                query!(
+                    "
+                    UPDATE buys
+                    SET used_amount = ?
+                    WHERE barcode_id = ? AND buy_id = ?
+",
+                    new_amount,
+                    id,
+                    buy_id
+                )
+                .execute(txn)
+                .await?;
+            }
+        }
+        Ok(())
+    }
+
+    async fn undo(self, txn: &mut sqlx::SqliteConnection) -> Result<(), undo::Error> {
+        match self {
+            Operation::Buy { buy_id, id } => {
+                let id = id.to_db();
+                let buy_id = buy_id.to_string();
+
+                query!(
+                    "
+                    DELETE FROM buys
+                    WHERE barcode_id = ? AND buy_id = ?
+",
+                    id,
+                    buy_id
+                )
+                .execute(txn)
+                .await?;
+            }
+            Operation::Consume { buy_id, id, amount } => {
+                todo!("We would need to subtract the amount.");
+            }
+        }
+        Ok(())
+    }
+}
+
+pub(crate) mod undo {
+    #[derive(thiserror::Error, Debug)]
+    pub(crate) enum Error {
+        #[error("Failed to execute undo sql statments: {0}")]
+        SqlError(#[from] sqlx::Error),
+    }
+}
+pub(crate) mod apply {
+    #[derive(thiserror::Error, Debug)]
+    pub(crate) enum Error {
+        #[error("Failed to execute apply sql statments: {0}")]
+        SqlError(#[from] sqlx::Error),
+    }
+}
+
+impl Barcode {
+    pub(crate) fn buy(&self, ops: &mut Operations<Operation>) {
+        let id = Uuid::new_v4();
+        ops.push(Operation::Buy {
+            buy_id: id,
+            id: self.id,
+        });
+    }
+
+    pub(crate) async fn consume(
+        &self,
+        app: &App,
+        amount: UnitAmount,
+        ops: &mut Operations<Operation>,
+    ) -> Result<(), consume::Error> {
+        assert_eq!(
+            self.amount.unit, amount.unit,
+            "We currently do not support unit conversions yet"
+        );
+
+        if amount.value > self.amount.value {
+            let foreign_amount_unit = Unit::from_id(app, amount.unit).await?;
+
+            if let Some(foreign_amount_unit) = foreign_amount_unit {
+                let self_amount_unit = Unit::from_id(app, self.amount.unit)
+                    .await?
+                    .expect("This unit id should always exist");
+
+                return Err(consume::Error::ConsumedMoreThanAvailable {
+                    consumed: Box::new((amount, foreign_amount_unit)),
+                    available: Box::new((self.amount, self_amount_unit)),
+                });
+            }
+
+            return Err(consume::Error::UnitIdDoesNotExist(amount.unit));
+        }
+
+        let barcode_id = self.id.to_db();
+        let buy_id = {
+            let record = query!(
+                "
+                SELECT buy_id
+                FROM buys
+                WHERE barcode_id = ? AND (used_amount IS NULL OR used_amount < ?)
+                ORDER BY timestamp DESC
+                LIMIT 1;
+",
+                barcode_id,
+                self.amount.value
+            )
+            .fetch_optional(&app.db)
+            .await?;
+
+            if let Some(found) = record {
+                Uuid::from_str(&found.buy_id).expect("Was a uuid, should still be one")
+            } else {
+                return Err(consume::Error::NoMoreAvailable);
+            }
+        };
+
+        ops.push(Operation::Consume {
+            id: self.id,
+            amount,
+            buy_id,
+        });
+
+        Ok(())
+    }
+}
+
+pub(crate) mod consume {
+    use actix_web::ResponseError;
+
+    use crate::storage::{
+        self,
+        sql::{
+            barcode::UnitAmount,
+            unit::{Unit, UnitId},
+        },
+    };
+
+    #[derive(thiserror::Error, Debug)]
+    pub(crate) enum Error {
+        #[error("Failed to execute apply sql statments: {0}")]
+        Sql(#[from] sqlx::Error),
+
+        #[error("Failed to fetch an unit from a specified amount id value")]
+        UnitGet(#[from] storage::sql::get::unit::from_id::Error),
+
+        #[error("The specified unit-id does not exist: {0}")]
+        UnitIdDoesNotExist(UnitId),
+
+        #[error("No more of this product is available, buy more. ")]
+        NoMoreAvailable,
+
+        #[error(
+            "Consumed more than available: consumed {} {}, but available: {} {}", consumed.0.value, consumed.1.short_name, available.0.value, available.1.short_name,
+        )]
+        ConsumedMoreThanAvailable {
+            consumed: Box<(UnitAmount, Unit)>,
+            available: Box<(UnitAmount, Unit)>,
+        },
+    }
+
+    impl ResponseError for Error {}
+}
diff --git a/crates/rocie-server/src/storage/sql/insert/mod.rs b/crates/rocie-server/src/storage/sql/insert/mod.rs
index eec6ad2..e6728d9 100644
--- a/crates/rocie-server/src/storage/sql/insert/mod.rs
+++ b/crates/rocie-server/src/storage/sql/insert/mod.rs
@@ -7,6 +7,7 @@ use log::{debug, trace};
 use serde::{Serialize, de::DeserializeOwned};
 use sqlx::{SqliteConnection, query};
 
+pub(crate) mod barcode;
 pub(crate) mod product;
 pub(crate) mod unit;
 
diff --git a/crates/rocie-server/src/storage/sql/insert/product/mod.rs b/crates/rocie-server/src/storage/sql/insert/product/mod.rs
index b6dd604..e14d3f4 100644
--- a/crates/rocie-server/src/storage/sql/insert/product/mod.rs
+++ b/crates/rocie-server/src/storage/sql/insert/product/mod.rs
@@ -3,8 +3,9 @@ use sqlx::query;
 use uuid::Uuid;
 
 use crate::storage::sql::{
+    barcode::Barcode,
     insert::{Operations, Transactionable},
-    product::{Barcode, Product, ProductId},
+    product::{Product, ProductId},
 };
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -47,7 +48,7 @@ impl Transactionable for Operation {
                 .await?;
             }
             Operation::AssociateBarcode { id, barcode } => {
-                let barcode_id = i64::from(barcode.id);
+                let barcode_id = barcode.id.to_db();
                 let barcode_amount_value = i64::from(barcode.amount.value);
                 let barcode_amount_unit = barcode.amount.unit;
 
@@ -90,7 +91,7 @@ impl Transactionable for Operation {
                 .await?;
             }
             Operation::AssociateBarcode { id, barcode } => {
-                let barcode_id = i64::from(barcode.id);
+                let barcode_id = barcode.id.to_db();
                 let barcode_amount_value = i64::from(barcode.amount.value);
                 let barcode_amount_unit = barcode.amount.unit;
 
diff --git a/crates/rocie-server/src/storage/sql/mod.rs b/crates/rocie-server/src/storage/sql/mod.rs
index f5ad88a..edce187 100644
--- a/crates/rocie-server/src/storage/sql/mod.rs
+++ b/crates/rocie-server/src/storage/sql/mod.rs
@@ -3,4 +3,6 @@ pub(crate) mod insert;
 
 // Types
 pub(crate) mod product;
+pub(crate) mod product_amount;
 pub(crate) mod unit;
+pub(crate) mod barcode;
diff --git a/crates/rocie-server/src/storage/sql/product.rs b/crates/rocie-server/src/storage/sql/product.rs
index e2a4f0d..93cc6a0 100644
--- a/crates/rocie-server/src/storage/sql/product.rs
+++ b/crates/rocie-server/src/storage/sql/product.rs
@@ -5,7 +5,7 @@ use sqlx::{Database, Encode, Type};
 use utoipa::ToSchema;
 use uuid::Uuid;
 
-use crate::storage::sql::unit::{Unit, UnitId};
+use crate::storage::sql::barcode::Barcode;
 
 #[derive(Clone, ToSchema, Serialize, Deserialize)]
 pub(crate) struct Product {
@@ -58,17 +58,3 @@ where
         <String as Type<DB>>::type_info()
     }
 }
-
-#[derive(ToSchema, Debug, Clone, Serialize, Deserialize)]
-pub(crate) struct Barcode {
-    #[schema(format = Int64, minimum = 0)]
-    pub(crate) id: u32,
-    pub(crate) amount: UnitAmount,
-}
-
-#[derive(ToSchema, Debug, Clone, Serialize, Deserialize)]
-pub(crate) struct UnitAmount {
-    #[schema(format = Int64, minimum = 0)]
-    pub(crate) value: u32,
-    pub(crate) unit: UnitId,
-}
diff --git a/crates/rocie-server/src/storage/sql/product_amount.rs b/crates/rocie-server/src/storage/sql/product_amount.rs
new file mode 100644
index 0000000..232c5db
--- /dev/null
+++ b/crates/rocie-server/src/storage/sql/product_amount.rs
@@ -0,0 +1,10 @@
+use serde::{Deserialize, Serialize};
+use utoipa::ToSchema;
+
+use crate::storage::sql::{barcode::UnitAmount, product::ProductId};
+
+#[derive(Clone, ToSchema, Serialize, Deserialize)]
+pub(crate) struct ProductAmount {
+    pub(crate) product_id: ProductId,
+    pub(crate) amount: UnitAmount,
+}
diff --git a/crates/rocie-server/tests/_testenv/init.rs b/crates/rocie-server/tests/_testenv/init.rs
new file mode 100644
index 0000000..5309fea
--- /dev/null
+++ b/crates/rocie-server/tests/_testenv/init.rs
@@ -0,0 +1,210 @@
+// yt - A fully featured command line YouTube client
+//
+// Copyright (C) 2025 Benedikt Peetz <benedikt.peetz@b-peetz.de>
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+// This file is part of Yt.
+//
+// You should have received a copy of the License along with this program.
+// If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
+
+use std::{
+    env,
+    ffi::OsStr,
+    fmt::Write,
+    fs, io, mem,
+    path::{Path, PathBuf},
+    process::{self, Stdio},
+    thread::sleep,
+    time::Duration,
+};
+
+use rocie_client::apis::configuration::Configuration;
+
+use crate::{_testenv::Paths, testenv::TestEnv};
+
+fn target_dir() -> PathBuf {
+    // Tests exe is in target/debug/deps, the *rocie-server* exe is in target/debug
+    env::current_exe()
+        .expect("./target/debug/deps/rocie-server-*")
+        .parent()
+        .expect("./target/debug/deps")
+        .parent()
+        .expect("./target/debug")
+        .parent()
+        .expect("./target")
+        .to_path_buf()
+}
+
+fn test_dir(name: &'static str, port: u32) -> PathBuf {
+    target_dir().join("tests").join(name).join(port.to_string())
+}
+
+fn prepare_files_and_dirs(test_dir: &Path) -> io::Result<Paths> {
+    fs::create_dir_all(test_dir)?;
+
+    let db_path = test_dir.join("database.sqlite");
+
+    {
+        // Remove all files, so that the test run stays pure
+        for entry in fs::read_dir(test_dir).unwrap() {
+            let entry = entry.unwrap();
+            let entry_ft = entry.file_type().unwrap();
+
+            if entry_ft.is_dir() {
+                fs::remove_dir_all(entry.path())?;
+            } else if entry_ft.is_file() {
+                fs::remove_file(entry.path())?;
+            } else {
+                panic!("Unknown file: {} ({entry_ft:#?})", entry.path().display());
+            }
+        }
+    }
+
+    Ok(Paths {
+        db: db_path,
+        test_dir: test_dir.to_owned(),
+    })
+}
+
+fn find_server_exe() -> PathBuf {
+    let target = target_dir().join("debug");
+
+    let exe_name = if cfg!(windows) {
+        "rocie-server.exe"
+    } else {
+        "rocie-server"
+    };
+
+    target.join(exe_name)
+}
+
+fn rocie_base_path(port: &str) -> String {
+    format!("http://127.0.0.1:{port}")
+}
+
+fn rocie_server_args<'a>(paths: &'a Paths, port: &'a str) -> [&'a OsStr; 5] {
+    [
+        OsStr::new("serve"),
+        OsStr::new("--db-path"),
+        paths.db.as_os_str(),
+        OsStr::new("--port"),
+        OsStr::new(port),
+    ]
+}
+
+impl TestEnv {
+    pub(crate) fn new(name: &'static str, port: u32) -> TestEnv {
+        let test_dir = test_dir(name, port);
+
+        let paths = prepare_files_and_dirs(&test_dir)
+            .inspect_err(|err| panic!("Error during test dir preparation: {err}"))
+            .unwrap();
+
+        let server_process = {
+            let server_exe = find_server_exe();
+            let mut cmd = process::Command::new(&server_exe);
+
+            cmd.current_dir(&paths.test_dir);
+
+            cmd.stdout(Stdio::piped());
+            cmd.stderr(Stdio::piped());
+
+            cmd.args(rocie_server_args(&paths, port.to_string().as_str()));
+
+            let child = cmd.spawn().expect("server spawn");
+
+            // Give the server time to start.
+            // TODO(@bpeetz): Use a better synchronization primitive <2025-09-11>
+            sleep(Duration::from_millis(240));
+
+            child
+        };
+
+        let config = {
+            let mut inner = Configuration::new();
+            inner.base_path = rocie_base_path(port.to_string().as_str());
+            inner.user_agent = Some(String::from("Rocie test driver"));
+            inner
+        };
+
+        let me = TestEnv {
+            name,
+            test_dir,
+            paths,
+            server_process: Some(server_process),
+            config,
+            port: port.to_string(),
+        };
+
+        me.log(format!("Starting test `{name}` on port `{port}`"));
+
+        me
+    }
+}
+
+impl Drop for TestEnv {
+    fn drop(&mut self) {
+        /// Format an error message for when the server did not exit successfully.
+        fn format_exit(args: &[&OsStr], output: &process::Output) -> String {
+            let mut base = String::new();
+
+            {
+                let args = args
+                    .iter()
+                    .map(|s| s.to_str().unwrap())
+                    .collect::<Vec<_>>()
+                    .join(" ");
+
+                if output.status.success() {
+                    writeln!(base, "`rocie-server {args}` did exit successfully.")
+                        .expect("In-memory");
+                } else {
+                    writeln!(base, "`rocie-server {args}` did not exit successfully.")
+                        .expect("In-memory");
+                }
+            }
+
+            let stdout = String::from_utf8_lossy(&output.stdout);
+            let stderr = String::from_utf8_lossy(&output.stderr);
+
+            if !stdout.is_empty() {
+                writeln!(base, "Stdout:\n---\n{stdout}\n---").expect("In-memory");
+            }
+            if !stderr.is_empty() {
+                writeln!(base, "Stderr:\n---\n{stderr}\n---").expect("In-memory");
+            }
+
+            base
+        }
+
+        {
+            // Stop the server process via SIGTERM.
+            let mut kill = process::Command::new("kill")
+                .args([
+                    "-s",
+                    "TERM",
+                    &self.server_process.as_ref().unwrap().id().to_string(),
+                ])
+                .spawn()
+                .unwrap();
+
+            eprintln!("Killing the server process");
+
+            kill.wait().unwrap();
+        }
+
+        let output = mem::take(&mut self.server_process)
+            .expect("Is some at this point")
+            .wait_with_output()
+            .expect("server exit output");
+
+        eprintln!(
+            "{}",
+            format_exit(
+                rocie_server_args(&self.paths, &self.port).as_slice(),
+                &output
+            )
+        );
+    }
+}
diff --git a/crates/rocie-server/tests/_testenv/log.rs b/crates/rocie-server/tests/_testenv/log.rs
new file mode 100644
index 0000000..9a07e78
--- /dev/null
+++ b/crates/rocie-server/tests/_testenv/log.rs
@@ -0,0 +1,72 @@
+use crate::testenv::TestEnv;
+
+macro_rules! request {
+    ($env:expr, $fn:ident ($($arg:expr),* $(,)?)) => {{
+        match request!(@call, $env, $fn, $($arg),*)  {
+            Ok(ok) => {
+                $env.log(format!("> {ok:?}"));
+
+                ok
+            },
+
+            Err(err) => {
+                $env.log(format!(">! {err:?}"));
+
+                panic!("Server request failed.");
+            }
+        }
+
+    }};
+
+    (@expect_error $reason:literal $env:expr, $fn:ident ($($arg:expr),* $(,)?)) => {{
+        match request!(@call, $env, $fn, $($arg),*)  {
+            Err(err) => {
+                $env.log(format!("> `{err}` ({})", $reason));
+
+                err
+            },
+
+            Ok(ok) => {
+                $env.log(format!(">? {ok:?}"));
+
+                panic!("Server request succeeded, but should fail.");
+            }
+        }
+    }};
+
+
+    (@call, $env:expr, $fn:ident, $($arg:expr),*) => {{
+        $env.log(
+            format!(
+                "< {}({})",
+                stringify!($fn),
+                request!(@format, $fn, $($arg),*)
+            )
+        );
+
+        $fn(&$env.config, $($arg),*).await
+    }};
+
+    (@format, $fn:ident, $($arg:expr),*) => {{
+          use std::fmt::Write;
+
+          let mut base = String::new();
+          $(
+              write!(base, "{:?}, ", $arg)
+              .expect("In memory write");
+          )*
+
+          base.trim().trim_end_matches(',').to_owned()
+    }};
+}
+
+pub(crate) use request;
+
+impl TestEnv {
+    pub(crate) fn log<A>(&self, message: A)
+    where
+        A: AsRef<str>,
+    {
+        eprintln!("{}: {}", self.name, message.as_ref());
+    }
+}
diff --git a/crates/rocie-server/tests/_testenv/mod.rs b/crates/rocie-server/tests/_testenv/mod.rs
new file mode 100644
index 0000000..a37925e
--- /dev/null
+++ b/crates/rocie-server/tests/_testenv/mod.rs
@@ -0,0 +1,23 @@
+//! This code was taken from *fd* at 30-06-2025.
+
+use std::{path::PathBuf, process};
+
+use rocie_client::apis::configuration::Configuration;
+
+mod init;
+pub(crate) mod log;
+
+/// Environment for the integration tests.
+pub(crate) struct TestEnv {
+    pub(crate) name: &'static str,
+    pub(crate) port: String,
+    pub(crate) test_dir: PathBuf,
+    pub(crate) paths: Paths,
+    pub(crate) server_process: Option<process::Child>,
+    pub(crate) config: Configuration,
+}
+
+pub(crate) struct Paths {
+    pub(crate) db: PathBuf,
+    pub(crate) test_dir: PathBuf,
+}
diff --git a/crates/rocie-server/tests/products/barcode.rs b/crates/rocie-server/tests/products/barcode.rs
new file mode 100644
index 0000000..c267006
--- /dev/null
+++ b/crates/rocie-server/tests/products/barcode.rs
@@ -0,0 +1,185 @@
+use rocie_client::{
+    apis::{
+        api_get_inventory_api::amount_by_id,
+        api_set_barcode_api::{buy_barcode, consume_barcode},
+    },
+    models::UnitAmount,
+};
+
+use crate::{
+    products::create_associated_barcode,
+    testenv::{TestEnv, log::request},
+};
+
+#[tokio::test]
+async fn test_barcode_buy() {
+    let env = TestEnv::new(module_path!(), 8087);
+
+    let barcode_id = 23;
+    let unit_value = 1;
+
+    let (unit_id, product_id) =
+        create_associated_barcode(&env, "Liter", "Milk", unit_value, barcode_id).await;
+
+    request!(env, buy_barcode(i32::try_from(barcode_id).unwrap()));
+
+    let product_amount = request!(env, amount_by_id(product_id.to_string().as_str()));
+
+    assert_eq!(product_amount.product_id, product_id);
+    assert_eq!(product_amount.amount.unit, unit_id);
+    assert_eq!(product_amount.amount.value, i64::from(unit_value));
+}
+
+#[tokio::test]
+async fn test_barcode_consume() {
+    let env = TestEnv::new(module_path!(), 8083);
+
+    let barcode_id = 23;
+    let unit_value = 1;
+
+    let (unit_id, product_id) =
+        create_associated_barcode(&env, "Liter", "Milk", unit_value, barcode_id).await;
+
+    request!(env, buy_barcode(i32::try_from(barcode_id).unwrap()));
+
+    request!(
+        env,
+        consume_barcode(
+            i32::try_from(barcode_id).unwrap(),
+            UnitAmount {
+                unit: unit_id,
+                value: 1,
+            },
+        )
+    );
+
+    let product_amount = request!(env, amount_by_id(product_id.to_string().as_str()));
+
+    assert_eq!(product_amount.product_id, product_id);
+    assert_eq!(product_amount.amount.unit, unit_id);
+    assert_eq!(product_amount.amount.value, 0);
+}
+
+#[tokio::test]
+async fn test_barcode_consume_error() {
+    let env = TestEnv::new(module_path!(), 8084);
+
+    let barcode_id = 23;
+    let unit_value = 1;
+
+    let (unit_id, product_id) =
+        create_associated_barcode(&env, "Liter", "Milk", unit_value, barcode_id).await;
+
+    request!(env, buy_barcode(i32::try_from(barcode_id).unwrap()));
+
+    request!(
+        @expect_error "We should not be able to consume more than available."
+        env,
+        consume_barcode(
+            i32::try_from(barcode_id).unwrap(),
+            UnitAmount {
+                unit: unit_id,
+                value: i64::from(unit_value + 1),
+            },
+        )
+    );
+
+    // Test, that the error does not actually go into the db.
+    let product_amount = request!(env, amount_by_id(product_id.to_string().as_str()));
+
+    assert_eq!(product_amount.product_id, product_id);
+    assert_eq!(product_amount.amount.unit, unit_id);
+    assert_eq!(product_amount.amount.value, i64::from(unit_value));
+}
+
+#[tokio::test]
+async fn test_barcode_consume_error_other() {
+    let env = TestEnv::new(module_path!(), 8085);
+
+    let barcode_id = 23;
+    let unit_value = 1;
+
+    let (unit_id, product_id) =
+        create_associated_barcode(&env, "Liter", "Milk", unit_value, barcode_id).await;
+
+    request!(env, buy_barcode(i32::try_from(barcode_id).unwrap()));
+
+    request!(
+        env,
+        consume_barcode(
+            i32::try_from(barcode_id).unwrap(),
+            UnitAmount {
+                unit: unit_id,
+                value: 1,
+            },
+        )
+    );
+
+    request!(
+        @expect_error "We already consumed everything, we bought"
+        env,
+        consume_barcode(
+            i32::try_from(barcode_id).unwrap(),
+            UnitAmount {
+                unit: unit_id,
+                value: 1,
+            },
+        )
+    );
+
+    // Test, that the error does not actually go into the db.
+    let product_amount = request!(env, amount_by_id(product_id.to_string().as_str()));
+
+    assert_eq!(product_amount.product_id, product_id);
+    assert_eq!(product_amount.amount.unit, unit_id);
+    assert_eq!(product_amount.amount.value, i64::from(0));
+}
+
+#[tokio::test]
+async fn test_barcode_multiple_buy_and_consume() {
+    let env = TestEnv::new(module_path!(), 8086);
+
+    let barcode_id = 23;
+    let unit_value = 1;
+
+    let (unit_id, product_id) =
+        create_associated_barcode(&env, "Liter", "Milk", unit_value, barcode_id).await;
+
+    request!(env, buy_barcode(i32::try_from(barcode_id).unwrap()));
+
+    request!(env, buy_barcode(i32::try_from(barcode_id).unwrap()));
+
+    env.log("Bought both barcodes");
+
+    request!(
+        env,
+        consume_barcode(
+            i32::try_from(barcode_id).unwrap(),
+            UnitAmount {
+                unit: unit_id,
+                value: 1,
+            },
+        )
+    );
+
+    env.log("Consumed first barcode");
+
+    request!(
+        env,
+        consume_barcode(
+            i32::try_from(barcode_id).unwrap(),
+            UnitAmount {
+                unit: unit_id,
+                value: 1,
+            },
+        )
+    );
+
+    env.log("Consumed second barcode");
+
+    let product_amount = request!(env, amount_by_id(product_id.to_string().as_str()));
+
+    assert_eq!(product_amount.product_id, product_id);
+    assert_eq!(product_amount.amount.unit, unit_id);
+    assert_eq!(product_amount.amount.value, i64::from(0));
+}
diff --git a/crates/rocie-server/tests/products/mod.rs b/crates/rocie-server/tests/products/mod.rs
new file mode 100644
index 0000000..e96ecc9
--- /dev/null
+++ b/crates/rocie-server/tests/products/mod.rs
@@ -0,0 +1,69 @@
+use rocie_client::{
+    apis::{
+        api_get_product_api::product_by_id,
+        api_set_product_api::{associate_barcode, register_product},
+        api_set_unit_api::register_unit,
+    },
+    models::{Barcode, Product, ProductStub, UnitAmount, UnitStub},
+};
+use uuid::Uuid;
+
+use crate::testenv::{TestEnv, log::request};
+
+mod barcode;
+mod register;
+
+async fn create_product(env: &TestEnv, name: &str) -> Uuid {
+    request!(
+        env,
+        register_product(ProductStub {
+            description: Some(None),
+            name: name.to_owned(),
+            parent: None,
+        },)
+    )
+}
+async fn create_unit(env: &TestEnv, name: &str) -> Uuid {
+    request!(
+        env,
+        register_unit(UnitStub {
+            description: Some(None),
+            full_name_plural: name.to_owned(),
+            full_name_singular: name.to_owned(),
+            short_name: name.to_owned(),
+        },)
+    )
+}
+
+async fn create_associated_barcode(
+    env: &TestEnv,
+    unit_name: &str,
+    product_name: &str,
+    barcode_value: u32,
+    barcode_id: u32,
+) -> (Uuid, Uuid) {
+    let unit_id = create_unit(env, unit_name).await;
+    let product_id = create_product(env, product_name).await;
+
+    request!(
+        env,
+        associate_barcode(
+            product_id.to_string().as_str(),
+            Barcode {
+                amount: Box::new(UnitAmount {
+                    unit: unit_id,
+                    value: i64::from(barcode_value),
+                }),
+                id: i32::try_from(barcode_id).unwrap(),
+            },
+        )
+    );
+
+    (unit_id, product_id)
+}
+
+async fn get_product(env: &TestEnv, id: Uuid) -> Product {
+    product_by_id(&env.config, id.to_string().as_str())
+        .await
+        .unwrap()
+}
diff --git a/crates/rocie-server/tests/products/register.rs b/crates/rocie-server/tests/products/register.rs
new file mode 100644
index 0000000..34f7b5c
--- /dev/null
+++ b/crates/rocie-server/tests/products/register.rs
@@ -0,0 +1,33 @@
+use rocie_client::{
+    apis::{api_get_product_api::product_by_id, api_set_product_api::register_product},
+    models::ProductStub,
+};
+
+use crate::testenv::{TestEnv, log::request};
+
+#[tokio::test]
+async fn test_product_register_roundtrip() {
+    let env = TestEnv::new(module_path!(), 8081);
+
+    let id = request!(
+        env,
+        register_product(ProductStub {
+            description: Some(Some("A soy based alternative to milk".to_owned())),
+            name: "Soy drink".to_owned(),
+            parent: None,
+        },)
+    );
+
+    let product = request!(env, product_by_id(id.to_string().as_str()));
+
+    assert_eq!(&product.name, "Soy drink");
+    assert_eq!(
+        product.description,
+        Some(Some("A soy based alternative to milk".to_owned()))
+    );
+    assert_eq!(product.id, id,);
+    // assert_eq!(
+    //     product.parent,
+    //     None,
+    // );
+}
diff --git a/crates/rocie-server/tests/tests.rs b/crates/rocie-server/tests/tests.rs
new file mode 100644
index 0000000..34395a6
--- /dev/null
+++ b/crates/rocie-server/tests/tests.rs
@@ -0,0 +1,6 @@
+#![allow(unused_crate_dependencies)]
+
+mod _testenv;
+pub(crate) use _testenv as testenv;
+
+mod products;