Detox MCP

Instructions

Implementation Reference

• src/tools/index.ts:405-426 (handler)

  MCP tool definition and handler for 'detox_generate_expectation'. Validates input using GenerateExpectationArgsSchema and generates code by calling generateExpectationCode.

  export const generateExpectationTool: Tool = {
    name: "detox_generate_expectation",
    description: "Generate Detox expectation/assertion code (toBeVisible, toHaveText, etc.).",
    inputSchema: zodToJsonSchema(GenerateExpectationArgsSchema),
    handler: async (args: z.infer<typeof GenerateExpectationArgsSchema>) => {
      const parsed = GenerateExpectationArgsSchema.parse(args);
  
      const code = generateExpectationCode({
        expectationType: parsed.expectationType,
        elementMatcher: parsed.elementMatcher,
        expectedValue: parsed.expectedValue,
        negated: parsed.negated,
        timeout: parsed.timeout,
        visibilityThreshold: parsed.visibilityThreshold,
      });
  
      return {
        success: true,
        code,
      };
    },
  };

• src/utils/validators.ts:142-161 (schema)

  Zod schema defining the input arguments for the detox_generate_expectation tool.

  export const GenerateExpectationArgsSchema = z.object({
    expectationType: z
      .enum([
        "toBeVisible",
        "toExist",
        "toBeFocused",
        "toHaveText",
        "toHaveLabel",
        "toHaveId",
        "toHaveValue",
        "toHaveSliderPosition",
        "toHaveToggleValue",
      ])
      .describe("Type of expectation"),
    elementMatcher: z.string().describe("Matcher code or description"),
    expectedValue: z.string().optional().describe("Expected value"),
    negated: z.boolean().optional().default(false),
    timeout: z.number().optional().describe("Custom timeout in ms"),
    visibilityThreshold: z.number().min(1).max(100).optional(),
  });

• src/templates/test-templates.ts:166-239 (helper)

  Core helper function that generates the Detox expectation code snippet based on provided options.

  export function generateExpectationCode(options: {
    expectationType:
      | "toBeVisible"
      | "toExist"
      | "toBeFocused"
      | "toHaveText"
      | "toHaveLabel"
      | "toHaveId"
      | "toHaveValue"
      | "toHaveSliderPosition"
      | "toHaveToggleValue";
    elementMatcher: string;
    expectedValue?: string | number | boolean;
    negated?: boolean;
    timeout?: number;
    visibilityThreshold?: number;
  }): string {
    const element = options.elementMatcher;
    const not = options.negated ? ".not" : "";
    let expectation: string;
  
    switch (options.expectationType) {
      case "toBeVisible":
        if (options.visibilityThreshold) {
          expectation = `toBeVisible(${options.visibilityThreshold})`;
        } else {
          expectation = "toBeVisible()";
        }
        break;
  
      case "toExist":
        expectation = "toExist()";
        break;
  
      case "toBeFocused":
        expectation = "toBeFocused()";
        break;
  
      case "toHaveText":
        expectation = `toHaveText('${options.expectedValue || ""}')`;
        break;
  
      case "toHaveLabel":
        expectation = `toHaveLabel('${options.expectedValue || ""}')`;
        break;
  
      case "toHaveId":
        expectation = `toHaveId('${options.expectedValue || ""}')`;
        break;
  
      case "toHaveValue":
        expectation = `toHaveValue('${options.expectedValue || ""}')`;
        break;
  
      case "toHaveSliderPosition":
        expectation = `toHaveSliderPosition(${options.expectedValue || 0})`;
        break;
  
      case "toHaveToggleValue":
        expectation = `toHaveToggleValue(${options.expectedValue ?? true})`;
        break;
  
      default:
        expectation = "toBeVisible()";
    }
  
    let code = `await expect(${element})${not}.${expectation};`;
  
    if (options.timeout) {
      code = `await waitFor(${element})${not}.${expectation}.withTimeout(${options.timeout});`;
    }
  
    return code;
  }

• src/tools/index.ts:428-442 (registration)

  Registration of the generateExpectationTool in the allTools array for MCP tool serving.

  // Export all tools
  export const allTools: Tool[] = [
    buildTool,
    testTool,
    initTool,
    readConfigTool,
    listConfigurationsTool,
    validateConfigTool,
    createConfigTool,
    listDevicesTool,
    generateTestTool,
    generateMatcherTool,
    generateActionTool,
    generateExpectationTool,
  ];