feat(apigateway): validate integrationHttpMethod with non-MOCK integration types (#28316)

`integrationHttpMethod` must be specified for non-MOCK integration types.
This PR adds validation to prevent [build-time errors](#6404).

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: lpizzinidev

packages/aws-cdk-lib/aws-apigateway/lib/integration.ts

@@ -167,6 +167,8 @@ export interface IntegrationConfig {
 
   /**
    * The integration's HTTP method type.
+   * Required unless you use a MOCK integration.
+   *
    * @default - no integration method specified.
    */
   readonly integrationHttpMethod?: string;
@@ -205,6 +207,10 @@ export class Integration {
     if (options.timeout && !options.timeout.isUnresolved() && (options.timeout.toMilliseconds() < 50 || options.timeout.toMilliseconds() > 29000)) {
       throw new Error('Integration timeout must be between 50 milliseconds and 29 seconds.');
     }
+
+    if (props.type !== IntegrationType.MOCK && !props.integrationHttpMethod) {
+      throw new Error('integrationHttpMethod is required for non-mock integration types.');
+    }
   }
 
   /**

packages/aws-cdk-lib/aws-apigateway/test/integration.test.ts

@@ -14,6 +14,7 @@ describe('integration', () => {
     // THEN
     expect(() => new apigw.Integration({
       type: apigw.IntegrationType.AWS_PROXY,
+      integrationHttpMethod: 'ANY',
       options: {
         credentialsPassthrough: true,
         credentialsRole: role,
@@ -229,4 +230,21 @@ describe('integration', () => {
 
   });
 
+  test('validates integrationHttpMethod is required for non-MOCK integration types', () => {
+    expect(() => new apigw.Integration({
+      type: apigw.IntegrationType.HTTP_PROXY,
+      options: {
+        timeout: cdk.Duration.seconds(15),
+      },
+    })).toThrow(/integrationHttpMethod is required for non-mock integration types/);
+  });
+
+  test('integrationHttpMethod can be omitted for MOCK integration type', () => {
+    expect(() => new apigw.Integration({
+      type: apigw.IntegrationType.MOCK,
+      options: {
+        timeout: cdk.Duration.seconds(15),
+      },
+    })).not.toThrow();
+  });
 });

packages/aws-cdk-lib/aws-apigateway/test/method.test.ts

@@ -140,7 +140,11 @@ describe('method', () => {
   test('use default integration from api', () => {
     // GIVEN
     const stack = new cdk.Stack();
-    const defaultIntegration = new apigw.Integration({ type: apigw.IntegrationType.HTTP_PROXY, uri: 'https://amazon.com' });
+    const defaultIntegration = new apigw.Integration({
+      type: apigw.IntegrationType.HTTP_PROXY,
+      integrationHttpMethod: 'POST',
+      uri: 'https://amazon.com',
+    });
     const api = new apigw.RestApi(stack, 'test-api', {
       cloudWatchRole: false,
       deploy: false,
@@ -309,6 +313,7 @@ describe('method', () => {
     // WHEN
     api.root.addMethod('GET', new apigw.Integration({
       type: apigw.IntegrationType.AWS_PROXY,
+      integrationHttpMethod: 'GET',
       options: {
         credentialsRole: role,
       },
@@ -331,6 +336,7 @@ describe('method', () => {
     // WHEN
     api.root.addMethod('GET', new apigw.Integration({
       type: apigw.IntegrationType.AWS_PROXY,
+      integrationHttpMethod: 'GET',
       options: {
         credentialsPassthrough: true,
       },