Add delete operation

postgres.go

@@ -52,3 +52,18 @@ func (c Client) Insert(
 
 	return nil
 }
+
+// Delete deletes one or more instances from the database by id
+func (c Client) Delete(
+	ctx context.Context,
+	entities ...interface{},
+) error {
+	for _, entity := range entities {
+		r := c.db.Table(c.tableName).Delete(entity)
+		if r.Error != nil {
+			return r.Error
+		}
+	}
+
+	return nil
+}

postgres_test.go

@@ -75,8 +75,7 @@ func TestInsert(t *testing.T) {
 			tableName: "users",
 		}
 
-		user := User{}
-		err = c.Insert(ctx, &user)
+		err = c.Insert(ctx)
 		assert.Equal(t, err, nil)
 	})
 
@@ -106,6 +105,56 @@ func TestInsert(t *testing.T) {
 	})
 }
 
+func TestDelete(t *testing.T) {
+	err := createTable()
+	if err != nil {
+		t.Fatal("could not create test table!")
+	}
+
+	t.Run("should ignore empty lists of users", func(t *testing.T) {
+		db := connectDB(t)
+		defer db.Close()
+
+		ctx := context.Background()
+		c := Client{
+			db:        db,
+			tableName: "users",
+		}
+
+		err = c.Delete(ctx)
+		assert.Equal(t, err, nil)
+	})
+
+	t.Run("should delete one user correctly", func(t *testing.T) {
+		db := connectDB(t)
+		defer db.Close()
+
+		ctx := context.Background()
+		c := Client{
+			db:        db,
+			tableName: "users",
+		}
+
+		u := User{
+			Name: "Fernanda",
+		}
+
+		err := c.Insert(ctx, &u)
+		assert.Equal(t, err, nil)
+
+		err = c.Delete(ctx, &u)
+		assert.Equal(t, err, nil)
+
+		result := User{}
+		it := c.db.Raw("SELECT * FROM users WHERE id=?", u.ID)
+		it.Scan(&result)
+
+		assert.Equal(t, it.Error, nil)
+		assert.Equal(t, uint(0), result.ID)
+		assert.Equal(t, "", result.Name)
+	})
+}
+
 func createTable() error {
 	db, err := gorm.Open("sqlite3", "/tmp/test.db")
 	if err != nil {