Add comprehensive TDD infrastructure with 45 tests

- Add lib crate exposing modules for integration testing
- Add dev-dependencies: tokio-test 0.4, tempfile
- Refactor parse_csv_fields() as pure function for unit testing
- Add field validation (minimum 16 fields required)
- Fix repository last_insert_id using SELECT LAST_INSERT_ID()
- Add 10 lib tests for CSV parsing and date formatting
- Add 10 config tests for environment configuration
- Add 7 import tests for CSV file parsing
- Add 6 models tests for database structs
- Add 12 repository tests for CRUD operations

tests/common/test_db.rs

@@ -0,0 +1,122 @@
+//! Test database utilities.
+//! 
+//! AI AGENT NOTE: These helpers manage the test database connection pool.
+//! Uses rusty_petroleum_test database for all tests.
+
+use sqlx::mysql::{MySqlPool, MySqlPoolOptions};
+use std::time::Duration;
+
+/// Creates a connection pool to the test database.
+/// 
+/// AI AGENT NOTE: Uses config.toml or config.test.toml for connection details.
+/// The test database should be separate from dev/prod to avoid data conflicts.
+pub async fn create_test_pool() -> MySqlPool {
+    let config = crate::config::Config::load(crate::config::Env::Test)
+        .expect("Failed to load test config");
+    
+    MySqlPoolOptions::new()
+        .max_connections(1)
+        .acquire_timeout(Duration::from_secs(10))
+        .connect(&config.database.connection_url())
+        .await
+        .expect("Failed to connect to test database")
+}
+
+/// Resets the test database by dropping and recreating all tables.
+/// 
+/// AI AGENT NOTE: This is used before running tests to ensure a clean state.
+/// It uses the `rusty_petroleum_test` database.
+pub async fn reset_test_database() -> anyhow::Result<()> {
+    let config = crate::config::Config::load(crate::config::Env::Test)?;
+    let database_url = config.database.connection_url();
+    let base_url = database_url.trim_end_matches(config.env.database_name());
+
+    let setup_pool = MySqlPoolOptions::new()
+        .max_connections(1)
+        .connect(base_url)
+        .await?;
+
+    // Drop database if exists
+    sqlx::query(&format!("DROP DATABASE IF EXISTS {}", config.env.database_name()))
+        .execute(&setup_pool)
+        .await?;
+
+    // Create fresh database
+    sqlx::query(&format!("CREATE DATABASE {}", config.env.database_name()))
+        .execute(&setup_pool)
+        .await?;
+
+    drop(setup_pool);
+
+    // Now create tables
+    let pool = create_test_pool().await;
+
+    // Create customers table
+    sqlx::query(
+        r#"
+        CREATE TABLE customers (
+            id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+            customer_number VARCHAR(50) NOT NULL UNIQUE,
+            card_report_group TINYINT UNSIGNED NOT NULL DEFAULT 0,
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+            INDEX idx_customer_number (customer_number)
+        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
+        "#,
+    )
+    .execute(&pool)
+    .await?;
+
+    // Create cards table
+    sqlx::query(
+        r#"
+        CREATE TABLE cards (
+            id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+            card_number VARCHAR(50) NOT NULL UNIQUE,
+            customer_id INT UNSIGNED NOT NULL,
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+            INDEX idx_card_number (card_number),
+            INDEX idx_customer_id (customer_id),
+            FOREIGN KEY (customer_id) REFERENCES customers(id)
+        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
+        "#,
+    )
+    .execute(&pool)
+    .await?;
+
+    // Create transactions table
+    sqlx::query(
+        r#"
+        CREATE TABLE transactions (
+            id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+            transaction_date DATETIME NOT NULL,
+            batch_number VARCHAR(20) NOT NULL,
+            amount DECIMAL(10,2) NOT NULL,
+            volume DECIMAL(10,3) NOT NULL,
+            price DECIMAL(8,4) NOT NULL,
+            quality_code INT NOT NULL,
+            quality_name VARCHAR(50) NOT NULL,
+            card_number VARCHAR(50) NOT NULL,
+            station VARCHAR(20) NOT NULL,
+            terminal VARCHAR(10) NOT NULL,
+            pump VARCHAR(10) NOT NULL,
+            receipt VARCHAR(20) NOT NULL,
+            control_number VARCHAR(20),
+            customer_id INT UNSIGNED NULL,
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            INDEX idx_transaction_date (transaction_date),
+            INDEX idx_batch_number (batch_number),
+            INDEX idx_customer_id (customer_id),
+            INDEX idx_card_number (card_number),
+            INDEX idx_station (station)
+        ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
+        "#,
+    )
+    .execute(&pool)
+    .await?;
+
+    drop(pool);
+
+    Ok(())
+}