feat: add category service with tests and ports

.sqlx/query-1e9dcba9a2b5a7e0bbb2b8c0d87166c24567420c5f7579aaa12b9d3d60c4e24d.json

@@ -0,0 +1,40 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                name, description, category_id, store_id\n             FROM\n                cqrs_inventory_category_query\n            WHERE\n                view_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "name",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 1,
+        "name": "description",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 2,
+        "name": "category_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 3,
+        "name": "store_id",
+        "type_info": "Uuid"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Text"
+      ]
+    },
+    "nullable": [
+      false,
+      true,
+      false,
+      false
+    ]
+  },
+  "hash": "1e9dcba9a2b5a7e0bbb2b8c0d87166c24567420c5f7579aaa12b9d3d60c4e24d"
+}

.sqlx/query-5944442c15d28d47654afae92815ccefea89cc9aee705e0e1e54a3bf884bb194.json

@@ -0,0 +1,23 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_inventory_category_query\n                WHERE\n                    name = $1\n                AND\n                    store_id = $2\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Text",
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "5944442c15d28d47654afae92815ccefea89cc9aee705e0e1e54a3bf884bb194"
+}

.sqlx/query-74313c3fbf8a5985b6deae21b56469fb66ddb078d016fd6f05cb5e62ef0b23d5.json

@@ -0,0 +1,28 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT \n                view_id, version\n             FROM\n                cqrs_inventory_category_query\n            WHERE\n                view_id = $1;",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "view_id",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 1,
+        "name": "version",
+        "type_info": "Int8"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Text"
+      ]
+    },
+    "nullable": [
+      false,
+      false
+    ]
+  },
+  "hash": "74313c3fbf8a5985b6deae21b56469fb66ddb078d016fd6f05cb5e62ef0b23d5"
+}

.sqlx/query-b70e7f74ae29d5e7cfdec133f1cedbd455d56875545f952efa261c99b0e7b4b4.json

@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT EXISTS (\n                SELECT 1\n                    FROM cqrs_inventory_category_query\n                WHERE\n                    category_id = $1\n            );",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "exists",
+        "type_info": "Bool"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Uuid"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "b70e7f74ae29d5e7cfdec133f1cedbd455d56875545f952efa261c99b0e7b4b4"
+}

.sqlx/query-c524c7fc3281e8ffe5d3d6f237d49cae596a9f621e6a64c31270d744406271ec.json

@@ -0,0 +1,19 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "UPDATE\n                        cqrs_inventory_category_query\n                    SET\n                        view_id = $1,\n                        version = $2,\n                        name = $3,\n                        description = $4,\n                        category_id = $5,\n                        store_id = $6;",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Text",
+        "Int8",
+        "Text",
+        "Text",
+        "Uuid",
+        "Uuid"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "c524c7fc3281e8ffe5d3d6f237d49cae596a9f621e6a64c31270d744406271ec"
+}

.sqlx/query-e66276ae53a3155b2a682a451bf4800f2ec7f777cc822cbe0866105def3e11af.json

@@ -0,0 +1,19 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "INSERT INTO cqrs_inventory_category_query (\n                        view_id, version, name, description, category_id, store_id\n                    ) VALUES (\n                        $1, $2, $3, $4, $5, $6\n                    );",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Left": [
+        "Text",
+        "Int8",
+        "Text",
+        "Text",
+        "Uuid",
+        "Uuid"
+      ]
+    },
+    "nullable": []
+  },
+  "hash": "e66276ae53a3155b2a682a451bf4800f2ec7f777cc822cbe0866105def3e11af"
+}

migrations/20240713073740_cqrs_inventory_category_query.sql

@@ -0,0 +1,36 @@
+-- SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+--
+-- SPDX-License-Identifier: AGPL-3.0-or-later
+
+CREATE TABLE IF NOT EXISTS categoty_events
+(
+    aggregate_type text                         NOT NULL,
+    aggregate_id   text                         NOT NULL,
+    sequence       bigint CHECK (sequence >= 0) NOT NULL,
+    event_type     text                         NOT NULL,
+    event_version  text                         NOT NULL,
+    payload        json                         NOT NULL,
+    metadata       json                         NOT NULL,
+    timestamp      timestamp with time zone DEFAULT (CURRENT_TIMESTAMP),
+    PRIMARY KEY (aggregate_type, aggregate_id, sequence)
+);
+
+CREATE TABLE IF NOT EXISTS cqrs_inventory_category_query
+(
+    view_id text                        NOT NULL,
+    version           bigint CHECK (version >= 0) NOT NULL,
+
+	name TEXT NOT NULL,
+	description TEXT,
+	store_id UUID NOT NULL,
+	deleted BOOLEAN NOT NULL DEFAULT FALSE,
+	category_id UUID NOT NULL UNIQUE,
+    UNIQUE(store_id, name),
+
+    PRIMARY KEY (view_id)
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS
+    cqrs_inventory_store_query_category_id_index
+ON
+    cqrs_inventory_category_query (category_id);

src/identity/application/aggregate.rs

@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 use async_trait::async_trait;
 use cqrs_es::Aggregate;
 

src/inventory/adapters/output/db/mod.rs

@@ -1 +1,5 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
 pub mod postgres;

src/inventory/adapters/output/db/postgres/category_exists.rs

@@ -0,0 +1,78 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use super::InventoryDBPostgresAdapter;
+use crate::inventory::application::port::output::db::{
+    errors::*, store_id_exists::*,
+};
+use crate::inventory::domain::store_aggregate::*;
+
+#[async_trait::async_trait]
+impl StoreIDExistsDBPort for InventoryDBPostgresAdapter {
+    async fn store_id_exists(&self, s: &Store) -> InventoryDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_inventory_store_query
+                WHERE
+                    store_id = $1
+            );",
+            s.store_id(),
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use uuid::Uuid;
+
+    use super::*;
+
+    #[actix_rt::test]
+    async fn test_postgres_store_exists() {
+        let store_id = Uuid::new_v4();
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::InventoryDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let store = StoreBuilder::default().name("store_name".into()).owner("store_owner".into())
+            .address(Some("store_address".into()))
+            .store_id(store_id)
+            .build().unwrap();
+
+        // state doesn't exist
+        assert!(!db.store_id_exists(&store).await.unwrap());
+
+        sqlx::query!(
+            "INSERT INTO cqrs_inventory_store_query
+                (view_id, version, name, address, store_id, owner)
+            VALUES ($1, $2, $3, $4, $5, $6);",
+            "1",
+            1,
+            store.name(),
+            store.address().as_ref().unwrap(),
+            store.store_id(),
+            store.owner(),
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+
+        // state exists
+        assert!(db.store_id_exists(&store).await.unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/inventory/adapters/output/db/postgres/category_id_exists.rs

@@ -0,0 +1,80 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use super::InventoryDBPostgresAdapter;
+use crate::inventory::application::port::output::db::{category_id_exists::*, errors::*};
+use crate::inventory::domain::category_aggregate::*;
+
+#[async_trait::async_trait]
+impl CategoryIDExistsDBPort for InventoryDBPostgresAdapter {
+    async fn category_id_exists(&self, s: &Category) -> InventoryDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_inventory_category_query
+                WHERE
+                    category_id = $1
+            );",
+            s.category_id(),
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use uuid::Uuid;
+
+    use super::*;
+
+    #[actix_rt::test]
+    async fn test_postgres_category_exists() {
+        let category_id = Uuid::new_v4();
+        let store_id = Uuid::new_v4();
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::InventoryDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let category = CategoryBuilder::default()
+            .name("category_name".into())
+            .description(Some("category_description".into()))
+            .category_id(category_id)
+            .store_id(store_id)
+            .build()
+            .unwrap();
+
+        // state doesn't exist
+        assert!(!db.category_id_exists(&category).await.unwrap());
+
+        sqlx::query!(
+            "INSERT INTO cqrs_inventory_category_query
+                (view_id, version, name, description, category_id, store_id)
+            VALUES ($1, $2, $3, $4, $5, $6);",
+            "1",
+            1,
+            category.name(),
+            category.description().as_ref().unwrap(),
+            category.category_id(),
+            category.store_id(),
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+
+        // state exists
+        assert!(db.category_id_exists(&category).await.unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/inventory/adapters/output/db/postgres/category_name_exists_for_store.rs

@@ -0,0 +1,85 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use super::InventoryDBPostgresAdapter;
+use crate::inventory::application::port::output::db::{
+    category_name_exists_for_store::*, errors::*,
+};
+use crate::inventory::domain::category_aggregate::*;
+
+#[async_trait::async_trait]
+impl CategoryNameExistsForStoreDBPort for InventoryDBPostgresAdapter {
+    async fn category_name_exists_for_store(&self, s: &Category) -> InventoryDBResult<bool> {
+        let res = sqlx::query!(
+            "SELECT EXISTS (
+                SELECT 1
+                    FROM cqrs_inventory_category_query
+                WHERE
+                    name = $1
+                AND
+                    store_id = $2
+            );",
+            s.name(),
+            s.store_id(),
+        )
+        .fetch_one(&self.pool)
+        .await?;
+        if let Some(x) = res.exists {
+            Ok(x)
+        } else {
+            Ok(false)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use uuid::Uuid;
+
+    use super::*;
+
+    #[actix_rt::test]
+    async fn test_postgres_category_exists() {
+        let category_id = Uuid::new_v4();
+        let store_id = Uuid::new_v4();
+        let settings = crate::settings::tests::get_settings().await;
+        settings.create_db().await;
+        let db = super::InventoryDBPostgresAdapter::new(
+            sqlx::postgres::PgPool::connect(&settings.database.url)
+                .await
+                .unwrap(),
+        );
+
+        let category = CategoryBuilder::default()
+            .name("category_name".into())
+            .description(Some("category_description".into()))
+            .category_id(category_id)
+            .store_id(store_id)
+            .build()
+            .unwrap();
+
+        // state doesn't exist
+        assert!(!db.category_name_exists_for_store(&category).await.unwrap());
+
+        sqlx::query!(
+            "INSERT INTO cqrs_inventory_category_query
+                (view_id, version, name, description, category_id, store_id)
+            VALUES ($1, $2, $3, $4, $5, $6);",
+            "1",
+            1,
+            category.name(),
+            category.description().as_ref().unwrap(),
+            category.category_id(),
+            category.store_id(),
+        )
+        .execute(&db.pool)
+        .await
+        .unwrap();
+
+        // state exists
+        assert!(db.category_name_exists_for_store(&category).await.unwrap());
+
+        settings.drop_db().await;
+    }
+}

src/inventory/adapters/output/db/postgres/category_view.rs

@@ -0,0 +1,175 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::persist::GenericQuery;
+use cqrs_es::persist::{PersistenceError, ViewContext, ViewRepository};
+use cqrs_es::{EventEnvelope, Query, View};
+use uuid::Uuid;
+
+use super::errors::*;
+use super::InventoryDBPostgresAdapter;
+use crate::inventory::domain::category_aggregate::Category;
+use crate::inventory::domain::events::InventoryEvent;
+use serde::{Deserialize, Serialize};
+
+// The view for a Category query, for a standard http application this should
+// be designed to reflect the response dto that will be returned to a user.
+#[derive(Debug, Default, Serialize, Deserialize)]
+pub struct CategoryView {
+    name: String,
+    description: Option<String>,
+    category_id: Uuid,
+    store_id: Uuid,
+}
+
+// This updates the view with events as they are committed.
+// The logic should be minimal here, e.g., don't calculate the account balance,
+// design the events to carry the balance information instead.
+impl View<Category> for CategoryView {
+    fn update(&mut self, event: &EventEnvelope<Category>) {
+        match &event.payload {
+            InventoryEvent::CategoryAdded(val) => {
+                self.name = val.name().into();
+                self.description = val.description().clone();
+                self.category_id = val.category_id().clone();
+                self.store_id = val.store_id().clone();
+            }
+            _ => (),
+        }
+    }
+}
+
+#[async_trait]
+impl ViewRepository<CategoryView, Category> for InventoryDBPostgresAdapter {
+    async fn load(&self, view_id: &str) -> Result<Option<CategoryView>, PersistenceError> {
+        let res = sqlx::query_as!(
+            CategoryView,
+            "SELECT 
+                name, description, category_id, store_id
+             FROM
+                cqrs_inventory_category_query
+            WHERE
+                view_id = $1;",
+            view_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+        Ok(Some(res))
+    }
+
+    async fn load_with_context(
+        &self,
+        view_id: &str,
+    ) -> Result<Option<(CategoryView, ViewContext)>, PersistenceError> {
+        let res = sqlx::query_as!(
+            CategoryView,
+            "SELECT 
+                name, description, category_id, store_id
+             FROM
+                cqrs_inventory_category_query
+            WHERE
+                view_id = $1;",
+            view_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        struct Context {
+            version: i64,
+            view_id: String,
+        }
+
+        let ctx = sqlx::query_as!(
+            Context,
+            "SELECT 
+                view_id, version
+             FROM
+                cqrs_inventory_category_query
+            WHERE
+                view_id = $1;",
+            view_id
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(PostgresAggregateError::from)?;
+
+        let view_context = ViewContext::new(ctx.view_id, ctx.version);
+        Ok(Some((res, view_context)))
+    }
+
+    async fn update_view(
+        &self,
+        view: CategoryView,
+        context: ViewContext,
+    ) -> Result<(), PersistenceError> {
+        match context.version {
+            0 => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "INSERT INTO cqrs_inventory_category_query (
+                        view_id, version, name, description, category_id, store_id
+                    ) VALUES (
+                        $1, $2, $3, $4, $5, $6
+                    );",
+                    context.view_instance_id,
+                    version,
+                    view.name,
+                    view.description,
+                    view.category_id,
+                    view.store_id,
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+            _ => {
+                let version = context.version + 1;
+                sqlx::query!(
+                    "UPDATE
+                        cqrs_inventory_category_query
+                    SET
+                        view_id = $1,
+                        version = $2,
+                        name = $3,
+                        description = $4,
+                        category_id = $5,
+                        store_id = $6;",
+                    context.view_instance_id,
+                    version,
+                    view.name,
+                    view.description,
+                    view.category_id,
+                    view.store_id
+                )
+                .execute(&self.pool)
+                .await
+                .map_err(PostgresAggregateError::from)?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+pub struct SimpleLoggingQuery {}
+
+// Our simplest query, this is great for debugging but absolutely useless in production.
+// This query just pretty prints the events as they are processed.
+#[async_trait]
+impl Query<Category> for SimpleLoggingQuery {
+    async fn dispatch(&self, aggregate_id: &str, events: &[EventEnvelope<Category>]) {
+        for event in events {
+            let payload = serde_json::to_string_pretty(&event.payload).unwrap();
+            println!("{}-{}\n{}", aggregate_id, event.sequence, payload);
+        }
+    }
+}
+
+// Our second query, this one will be handled with Postgres `GenericQuery`
+// which will serialize and persist our view after it is updated. It also
+// provides a `load` method to deserialize the view on request.
+pub type CategoryQuery = GenericQuery<InventoryDBPostgresAdapter, CategoryView, Category>;

src/inventory/adapters/output/db/postgres/mod.rs

@@ -1,12 +1,16 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+
 use std::sync::Arc;
 
 use sqlx::postgres::PgPool;
 
 use crate::db::{migrate::RunMigrations, sqlx_postgres::Postgres};
 
+mod category_id_exists;
+mod category_name_exists_for_store;
+mod category_view;
 mod errors;
 mod store_id_exists;
 mod store_view;

src/inventory/application/port/output/db/category_id_exists.rs

@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+
+use crate::inventory::domain::category_aggregate::Category;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait CategoryIDExistsDBPort: Send + Sync {
+    async fn category_id_exists(&self, c: &Category) -> InventoryDBResult<bool>;
+}
+
+pub type CategoryIDExistsDBPortObj = std::sync::Arc<dyn CategoryIDExistsDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_category_id_exists_db_port_false(
+        times: Option<usize>,
+    ) -> CategoryIDExistsDBPortObj {
+        let mut m = MockCategoryIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_category_id_exists()
+                .times(times)
+                .returning(|_| Ok(false));
+        } else {
+            m.expect_category_id_exists().returning(|_| Ok(false));
+        }
+
+        Arc::new(m)
+    }
+
+    pub fn mock_category_id_exists_db_port_true(times: Option<usize>) -> CategoryIDExistsDBPortObj {
+        let mut m = MockCategoryIDExistsDBPort::new();
+        if let Some(times) = times {
+            m.expect_category_id_exists()
+                .times(times)
+                .returning(|_| Ok(true));
+        } else {
+            m.expect_category_id_exists().returning(|_| Ok(true));
+        }
+
+        Arc::new(m)
+    }
+}

src/inventory/application/port/output/db/category_name_exists_for_store.rs

@@ -0,0 +1,60 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use mockall::predicate::*;
+use mockall::*;
+
+use crate::inventory::domain::category_aggregate::Category;
+
+use super::errors::*;
+#[cfg(test)]
+#[allow(unused_imports)]
+pub use tests::*;
+
+#[automock]
+#[async_trait::async_trait]
+pub trait CategoryNameExistsForStoreDBPort: Send + Sync {
+    async fn category_name_exists_for_store(&self, c: &Category) -> InventoryDBResult<bool>;
+}
+
+pub type CategoryNameExistsForStoreDBPortObj = std::sync::Arc<dyn CategoryNameExistsForStoreDBPort>;
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+
+    use std::sync::Arc;
+
+    pub fn mock_category_name_exists_for_store_db_port_false(
+        times: Option<usize>,
+    ) -> CategoryNameExistsForStoreDBPortObj {
+        let mut m = MockCategoryNameExistsForStoreDBPort::new();
+        if let Some(times) = times {
+            m.expect_category_name_exists_for_store()
+                .times(times)
+                .returning(|_| Ok(false));
+        } else {
+            m.expect_category_name_exists_for_store()
+                .returning(|_| Ok(false));
+        }
+
+        Arc::new(m)
+    }
+
+    pub fn mock_category_name_exists_for_store_db_port_true(
+        times: Option<usize>,
+    ) -> CategoryNameExistsForStoreDBPortObj {
+        let mut m = MockCategoryNameExistsForStoreDBPort::new();
+        if let Some(times) = times {
+            m.expect_category_name_exists_for_store()
+                .times(times)
+                .returning(|_| Ok(true));
+        } else {
+            m.expect_category_name_exists_for_store()
+                .returning(|_| Ok(true));
+        }
+
+        Arc::new(m)
+    }
+}

src/inventory/application/port/output/db/mod.rs

@@ -2,6 +2,7 @@
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
-//pub mod category_exists;
+pub mod category_id_exists;
+pub mod category_name_exists_for_store;
 pub mod errors;
 pub mod store_id_exists;

src/inventory/application/services/add_category_service.rs

@@ -1,9 +1,11 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+use std::sync::Arc;
 
 use derive_builder::Builder;
-use uuid::Uuid;
+use mockall::predicate::*;
+use mockall::*;
 
 use super::errors::*;
 use crate::inventory::{
@@ -16,12 +18,13 @@ use crate::inventory::{
 };
 use crate::utils::uuid::*;
 
+#[automock]
 #[async_trait::async_trait]
 pub trait AddCategoryUseCase: Send + Sync {
     async fn add_category(&self, cmd: AddCategoryCommand) -> InventoryResult<CategoryAddedEvent>;
 }
 
-pub type AddCategoryServiceObj = std::sync::Arc<dyn AddCategoryUseCase>;
+pub type AddCategoryServiceObj = Arc<dyn AddCategoryUseCase>;
 
 #[derive(Clone, Builder)]
 pub struct AddCategoryService {
@@ -83,7 +86,7 @@ impl AddCategoryUseCase for AddCategoryService {
 }
 
 #[cfg(test)]
-mod tests {
+pub mod tests {
     use super::*;
 
     use uuid::Uuid;
@@ -91,6 +94,32 @@ mod tests {
     use crate::utils::uuid::tests::UUID;
     use crate::{tests::bdd::*, utils::uuid::tests::mock_get_uuid};
 
+    pub fn mock_add_category_service(
+        times: Option<usize>,
+        cmd: AddCategoryCommand,
+    ) -> AddCategoryServiceObj {
+        let mut m = MockAddCategoryUseCase::new();
+
+        let res = CategoryAddedEventBuilder::default()
+            .name(cmd.name().into())
+            .description(cmd.description().as_ref().map(|s| s.to_string()))
+            .added_by_user(cmd.adding_by().into())
+            .store_id(cmd.store_id().clone())
+            .category_id(UUID.clone())
+            .build()
+            .unwrap();
+
+        if let Some(times) = times {
+            m.expect_add_category()
+                .times(times)
+                .returning(move |_| Ok(res.clone()));
+        } else {
+            m.expect_add_category().returning(move |_| Ok(res.clone()));
+        }
+
+        Arc::new(m)
+    }
+
     #[actix_rt::test]
     async fn test_service_category_doesnt_exist() {
         let name = "foo";

src/inventory/application/services/mod.rs

@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
+
 use derive_builder::Builder;
 use mockall::predicate::*;
 use mockall::*;
@@ -8,26 +9,26 @@ use mockall::*;
 pub mod errors;
 
 // services
-//pub mod add_category_service;
+pub mod add_category_service;
 pub mod add_store_service;
 
 #[automock]
 pub trait InventoryServicesInterface: Send + Sync {
     fn add_store(&self) -> add_store_service::AddStoreServiceObj;
-    //   fn add_category(&self) -> add_category_service::AddCategoryServiceObj;
+    fn add_category(&self) -> add_category_service::AddCategoryServiceObj;
 }
 
 #[derive(Clone, Builder)]
 pub struct InventoryServices {
     add_store: add_store_service::AddStoreServiceObj,
-    //    add_category: add_category_service::AddCategoryServiceObj,
+    add_category: add_category_service::AddCategoryServiceObj,
 }
 
 impl InventoryServicesInterface for InventoryServices {
     fn add_store(&self) -> add_store_service::AddStoreServiceObj {
         self.add_store.clone()
     }
-    //   fn add_category(&self) -> add_category_service::AddCategoryServiceObj {
-    //       self.add_category.clone()
-    //   }
+    fn add_category(&self) -> add_category_service::AddCategoryServiceObj {
+        self.add_category.clone()
+    }
 }

src/inventory/domain/add_category_command.rs

@@ -0,0 +1,98 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_getters::Getters;
+use derive_more::{Display, Error};
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+#[derive(Debug, Error, Display, Clone, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+pub enum AddCategoryCommandError {
+    NameIsEmpty,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters)]
+pub struct AddCategoryCommand {
+    name: String,
+    description: Option<String>,
+    store_id: Uuid,
+    adding_by: String,
+}
+
+impl AddCategoryCommand {
+    pub fn new(
+        name: String,
+        description: Option<String>,
+        store_id: Uuid,
+        adding_by: String,
+    ) -> Result<Self, AddCategoryCommandError> {
+        let description: Option<String> = if let Some(description) = description {
+            let description = description.trim();
+            if description.is_empty() {
+                None
+            } else {
+                Some(description.to_owned())
+            }
+        } else {
+            None
+        };
+
+        let name = name.trim().to_owned();
+        if name.is_empty() {
+            return Err(AddCategoryCommandError::NameIsEmpty);
+        }
+
+        Ok(Self {
+            name,
+            store_id,
+            description,
+            adding_by,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_cmd() {
+        let name = "foo";
+        let description = "bar";
+        let username = "baz";
+        let store_id = Uuid::new_v4();
+
+        // description = None
+        let cmd =
+            AddCategoryCommand::new(name.into(), None, store_id.clone(), username.into()).unwrap();
+        assert_eq!(cmd.name(), name);
+        assert_eq!(cmd.description(), &None);
+        assert_eq!(cmd.adding_by(), username);
+        assert_eq!(cmd.store_id(), &store_id);
+
+        // description = Some
+        let cmd = AddCategoryCommand::new(
+            name.into(),
+            Some(description.into()),
+            store_id.clone(),
+            username.into(),
+        )
+        .unwrap();
+        assert_eq!(cmd.name(), name);
+        assert_eq!(cmd.description(), &Some(description.to_owned()));
+        assert_eq!(cmd.adding_by(), username);
+        assert_eq!(cmd.store_id(), &store_id);
+
+        // AddCategoryCommandError::NameIsEmpty
+        assert_eq!(
+            AddCategoryCommand::new(
+                "".into(),
+                Some(description.into()),
+                store_id.clone(),
+                username.into()
+            ),
+            Err(AddCategoryCommandError::NameIsEmpty)
+        )
+    }
+}

src/inventory/domain/category_added_event.rs

@@ -0,0 +1,19 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+#[derive(
+    Clone, Debug, Builder, Serialize, Deserialize, Getters, Eq, PartialEq, Ord, PartialOrd,
+)]
+pub struct CategoryAddedEvent {
+    name: String,
+    description: Option<String>,
+    added_by_user: String,
+    category_id: Uuid,
+    store_id: Uuid,
+}

src/inventory/domain/category_aggregate.rs

@@ -0,0 +1,128 @@
+// SPDX-FileCopyrightText: 2024 Aravinth Manivannan <realaravinth@batsense.net>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use async_trait::async_trait;
+use cqrs_es::Aggregate;
+use derive_builder::Builder;
+use derive_getters::Getters;
+use serde::{Deserialize, Serialize};
+use uuid::Uuid;
+
+use crate::inventory::application::services::errors::*;
+use crate::inventory::application::services::InventoryServicesInterface;
+
+use super::{commands::InventoryCommand, events::InventoryEvent};
+
+#[derive(
+    Clone, Debug, Serialize, Default, Deserialize, Eq, PartialEq, Ord, PartialOrd, Getters, Builder,
+)]
+pub struct Category {
+    name: String,
+    description: Option<String>,
+    store_id: Uuid,
+    category_id: Uuid,
+}
+
+#[async_trait]
+impl Aggregate for Category {
+    type Command = InventoryCommand;
+    type Event = InventoryEvent;
+    type Error = InventoryError;
+    type Services = std::sync::Arc<dyn InventoryServicesInterface>;
+
+    // This identifier should be unique to the system.
+    fn aggregate_type() -> String {
+        "inventory.category".to_string()
+    }
+
+    // The aggregate logic goes here. Note that this will be the _bulk_ of a CQRS system
+    // so expect to use helper functions elsewhere to keep the code clean.
+    async fn handle(
+        &self,
+        command: Self::Command,
+        services: &Self::Services,
+    ) -> Result<Vec<Self::Event>, Self::Error> {
+        match command {
+            InventoryCommand::AddCategory(cmd) => {
+                let res = services.add_category().add_category(cmd).await?;
+                Ok(vec![InventoryEvent::CategoryAdded(res)])
+            }
+            _ => Ok(Vec::default()),
+        }
+    }
+
+    fn apply(&mut self, event: Self::Event) {
+        match event {
+            InventoryEvent::CategoryAdded(e) => {
+                *self = CategoryBuilder::default()
+                    .name(e.name().into())
+                    .category_id(e.category_id().clone())
+                    .description(e.description().clone())
+                    .store_id(e.store_id().clone())
+                    .build()
+                    .unwrap();
+            }
+            _ => (),
+        }
+    }
+}
+
+#[cfg(test)]
+mod aggregate_tests {
+    use std::sync::Arc;
+
+    use cqrs_es::test::TestFramework;
+    use uuid::Uuid;
+
+    use super::*;
+    use crate::inventory::{
+        application::services::{add_category_service::tests::*, *},
+        domain::{
+            add_category_command::*, category_added_event::*, commands::InventoryCommand,
+            events::InventoryEvent,
+        },
+    };
+    use crate::tests::bdd::*;
+    use crate::utils::uuid::tests::*;
+
+    type CategoryTestFramework = TestFramework<Category>;
+
+    #[test]
+    fn test_create_store() {
+        let name = "category_name";
+        let description = Some("category_description".to_string());
+        let adding_by = "store_owner";
+        let store_id = Uuid::new_v4();
+        let category_id = UUID.clone();
+
+        let cmd = AddCategoryCommand::new(
+            name.into(),
+            description.clone(),
+            store_id.clone(),
+            adding_by.into(),
+        )
+        .unwrap();
+
+        let expected = CategoryAddedEventBuilder::default()
+            .name(cmd.name().into())
+            .description(cmd.description().as_ref().map(|s| s.to_string()))
+            .added_by_user(cmd.adding_by().into())
+            .store_id(cmd.store_id().clone())
+            .category_id(category_id.clone())
+            .build()
+            .unwrap();
+        let expected = InventoryEvent::CategoryAdded(expected);
+
+        let mut services = MockInventoryServicesInterface::new();
+        services
+            .expect_add_category()
+            .times(IS_CALLED_ONLY_ONCE.unwrap())
+            .return_const(mock_add_category_service(IS_CALLED_ONLY_ONCE, cmd.clone()));
+
+        CategoryTestFramework::with(Arc::new(services))
+            .given_no_previous_events()
+            .when(InventoryCommand::AddCategory(cmd))
+            .then_expect_events(vec![expected]);
+    }
+}

src/inventory/domain/commands.rs

@@ -5,13 +5,10 @@
 use mockall::predicate::*;
 use serde::{Deserialize, Serialize};
 
-use super::{
-    // add_category_command::AddCategoryCommand,
-    add_store_command::AddStoreCommand,
-};
+use super::{add_category_command::AddCategoryCommand, add_store_command::AddStoreCommand};
 
 #[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd)]
 pub enum InventoryCommand {
-    //AddCategory(AddCategoryCommand),
+    AddCategory(AddCategoryCommand),
     AddStore(AddStoreCommand),
 }

src/inventory/domain/events.rs

@@ -5,14 +5,11 @@
 use cqrs_es::DomainEvent;
 use serde::{Deserialize, Serialize};
 
-use super::{
-    // category_added_event::*,
-    store_added_event::StoreAddedEvent,
-};
+use super::{category_added_event::*, store_added_event::StoreAddedEvent};
 
 #[derive(Clone, Debug, Serialize, Deserialize, Eq, PartialEq, Ord, PartialOrd)]
 pub enum InventoryEvent {
-    //    CategoryAdded(CategoryAddedEvent),
+    CategoryAdded(CategoryAddedEvent),
     StoreAdded(StoreAddedEvent),
 }
 
@@ -25,7 +22,7 @@ impl DomainEvent for InventoryEvent {
 
     fn event_type(&self) -> String {
         let e: &str = match self {
-            //           InventoryEvent::CategoryAdded { .. } => "InventoryCategoryAdded",
+            InventoryEvent::CategoryAdded { .. } => "InventoryCategoryAdded",
             InventoryEvent::StoreAdded { .. } => "InventoryStoredded",
         };
 

src/inventory/domain/mod.rs

@@ -5,15 +5,16 @@
 // aggregates
 //pub mod money_aggregate;
 //pub mod product_aggregate;
+pub mod category_aggregate;
 //pub mod stock_aggregate;
 pub mod store_aggregate;
 
 // commands
-//pub mod add_category_command;
+pub mod add_category_command;
 pub mod add_store_command;
 pub mod commands;
 
 // events
-//pub mod category_added_event;
+pub mod category_added_event;
 pub mod events;
 pub mod store_added_event;

src/inventory/domain/store_aggregate.rs

@@ -72,9 +72,7 @@ impl Aggregate for Store {
         }
     }
 }
-// The aggregate tests are the most important part of a CQRS system.
-// The simplicity and flexibility of these tests are a good part of what
-// makes an event sourced system so friendly to changing business requirements.
+
 #[cfg(test)]
 mod aggregate_tests {
     use std::sync::Arc;