Implement POST task (#28)

Closes #21

Reviewed-on: #28

backend/api_test.go

@@ -205,3 +205,80 @@ func TestDeleteUserGoalInvalidId(t *testing.T) {
 		Status(400).
 		JSON().Object().Value("error").IsEqual("Invalid goal ID")
 }
+
+func TestCreateTask(t *testing.T) {
+	e := startServer(t)
+
+	// Create a new task without assigned user
+	requestBody := map[string]interface{}{
+		"name":   "Test Task",
+		"reward": 100,
+	}
+
+	response := e.POST("/tasks").
+		WithJSON(requestBody).
+		Expect().
+		Status(201). // Expect Created status
+		JSON().Object()
+
+	// Verify the response has an ID
+	response.ContainsKey("id")
+	taskId := response.Value("id").Number().Raw()
+
+	// Create a new task with assigned user
+	assignedUserId := 1
+	requestBodyWithUser := map[string]interface{}{
+		"name":     "Test Task Assigned",
+		"reward":   200,
+		"assigned": assignedUserId,
+	}
+
+	responseWithUser := e.POST("/tasks").
+		WithJSON(requestBodyWithUser).
+		Expect().
+		Status(201).
+		JSON().Object()
+
+	responseWithUser.ContainsKey("id")
+	responseWithUser.Value("id").Number().NotEqual(taskId) // Ensure different ID
+}
+
+func TestCreateTaskNoName(t *testing.T) {
+	e := startServer(t)
+
+	requestBody := map[string]interface{}{
+		"reward": 100,
+	}
+
+	e.POST("/tasks").WithJSON(requestBody).Expect().Status(400)
+}
+
+func TestCreateTaskInvalidAssignedUser(t *testing.T) {
+	e := startServer(t)
+
+	requestBody := map[string]interface{}{
+		"name":     "Test Task Invalid User",
+		"reward":   100,
+		"assigned": 999, // Non-existent user ID
+	}
+
+	e.POST("/tasks").
+		WithJSON(requestBody).
+		Expect().
+		Status(404). // Expect Not Found
+		JSON().Object().Value("error").IsEqual(ErrUserNotFound)
+}
+
+func TestCreateTaskInvalidRequestBody(t *testing.T) {
+	e := startServer(t)
+
+	// Test with missing fields (name is required)
+	invalidRequest := map[string]interface{}{
+		"reward": 5000,
+	}
+
+	e.POST("/tasks").
+		WithJSON(invalidRequest).
+		Expect().
+		Status(400)
+}