Replicate "too many feature flags" error in test

src/feature-flags.test.ts

@@ -21,6 +21,7 @@ import {
   mockFeatureFlagApiEndpoint,
   setupActionsVars,
   setupTests,
+  stubFeatureFlagApiEndpoint,
 } from "./testing-utils";
 import { ToolsFeature } from "./tools-features";
 import * as util from "./util";
@@ -132,6 +133,35 @@ test("Features use default value if they're not returned in API response", async
   });
 });
 
+test("Include no more than 25 features in each API request", async (t) => {
+  await withTmpDir(async (tmpDir) => {
+    const features = setUpFeatureFlagTests(tmpDir);
+
+    stubFeatureFlagApiEndpoint((request) => {
+      const requestedFeatures = (request.features as string).split(",");
+      return {
+        status: requestedFeatures.length <= 25 ? 200 : 400,
+        messageIfError: "Can request a maximum of 25 features.",
+        data: {},
+      };
+    });
+
+    // We only need to call getValue once, and it does not matter which feature
+    // we ask for. Under the hood, the features library will request all features
+    // from the API.
+    const feature = Object.values(Feature)[0];
+    // TODO: change to `t.notThrowsAsync` once we implement request chunking.
+    await t.throwsAsync(
+      async () => features.getValue(feature, includeCodeQlIfRequired(feature)),
+      {
+        message:
+          "Encountered an error while trying to determine feature enablement: " +
+          "Error: Can request a maximum of 25 features.",
+      },
+    );
+  });
+});
+
 test("Feature flags exception is propagated if the API request errors", async (t) => {
   await withTmpDir(async (tmpDir) => {
     const features = setUpFeatureFlagTests(tmpDir);

src/testing-utils.ts

@@ -180,6 +180,21 @@ export function getRecordingLogger(messages: LoggedMessage[]): Logger {
 export function mockFeatureFlagApiEndpoint(
   responseStatusCode: number,
   response: { [flagName: string]: boolean },
+) {
+  stubFeatureFlagApiEndpoint(() => ({
+    status: responseStatusCode,
+    messageIfError: "some error message",
+    data: response,
+  }));
+}
+
+/** Stub the HTTP request to the feature flags enablement API endpoint. */
+export function stubFeatureFlagApiEndpoint(
+  responseFunction: (params: any) => {
+    status: number;
+    messageIfError?: string;
+    data: { [flagName: string]: boolean };
+  },
 ) {
   // Passing an auth token is required, so we just use a dummy value
   const client = github.getOctokit("123");
@@ -189,16 +204,23 @@ export function mockFeatureFlagApiEndpoint(
   const optInSpy = requestSpy.withArgs(
     "GET /repos/:owner/:repo/code-scanning/codeql-action/features",
   );
-  if (responseStatusCode < 300) {
-    optInSpy.resolves({
-      status: responseStatusCode,
-      data: response,
-      headers: {},
-      url: "GET /repos/:owner/:repo/code-scanning/codeql-action/features",
-    });
-  } else {
-    optInSpy.throws(new HTTPError("some error message", responseStatusCode));
-  }
+
+  optInSpy.callsFake((_route, params) => {
+    const response = responseFunction(params);
+    if (response.status < 300) {
+      return Promise.resolve({
+        status: response.status,
+        data: response.data,
+        headers: {},
+        url: "GET /repos/:owner/:repo/code-scanning/codeql-action/features",
+      });
+    } else {
+      throw new HTTPError(
+        response.messageIfError || "default stub error message",
+        response.status,
+      );
+    }
+  });
 
   sinon.stub(apiClient, "getApiClient").value(() => client);
 }