Implement internal mail skill MVP

internal/db/db_test.go

@@ -0,0 +1,33 @@
+package db
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+)
+
+func TestOpenAndMigrateCreatesCoreTables(t *testing.T) {
+	store, err := Open(":memory:")
+	if err != nil {
+		t.Fatalf("Open() error = %v", err)
+	}
+	defer store.Close()
+
+	if err := store.Migrate(context.Background()); err != nil {
+		t.Fatalf("Migrate() error = %v", err)
+	}
+
+	var name string
+	err = store.DB.QueryRowContext(context.Background(), "SELECT name FROM sqlite_master WHERE type='table' AND name='mail_messages'").Scan(&name)
+	if err != nil {
+		t.Fatalf("mail_messages table missing: %v", err)
+	}
+
+	err = store.DB.QueryRowContext(context.Background(), "SELECT name FROM sqlite_master WHERE type='table' AND name='sent_messages'").Scan(&name)
+	if err != nil && err != sql.ErrNoRows {
+		t.Fatalf("sent_messages lookup failed: %v", err)
+	}
+	if name != "sent_messages" {
+		t.Fatalf("sent_messages table missing, got %q", name)
+	}
+}