Ignore default version flags with invalid version numbers

src/feature-flags.test.ts

@@ -423,6 +423,38 @@ test(`selects CLI v2.11.6 on Dotcom when no default version feature flags are en
   });
 });
 
+test("ignores invalid version numbers in default version feature flags", async (t) => {
+  await withTmpDir(async (tmpDir) => {
+    const loggedMessages = [];
+    const featureEnablement = setUpFeatureFlagTests(
+      tmpDir,
+      getRecordingLogger(loggedMessages)
+    );
+    const expectedFeatureEnablement = initializeFeatures(true);
+    expectedFeatureEnablement["default_codeql_version_2_12_0_enabled"] = true;
+    expectedFeatureEnablement["default_codeql_version_2_12_1_enabled"] = true;
+    expectedFeatureEnablement["default_codeql_version_2_12_invalid_enabled"] =
+      true;
+    mockFeatureFlagApiEndpoint(200, expectedFeatureEnablement);
+
+    t.deepEqual(
+      await featureEnablement.getDefaultCliVersion(GitHubVariant.DOTCOM),
+      {
+        cliVersion: "2.12.1",
+        variant: GitHubVariant.DOTCOM,
+      }
+    );
+    t.assert(
+      loggedMessages.find(
+        (v: LoggedMessage) =>
+          v.type === "warning" &&
+          v.message ===
+            "Ignoring feature flag default_codeql_version_2_12_invalid_enabled as it does not specify a valid CodeQL version."
+      ) !== undefined
+    );
+  });
+});
+
 function assertAllFeaturesUndefinedInApi(
   t: ExecutionContext<unknown>,
   loggedMessages: LoggedMessage[]

src/feature-flags.ts

@@ -1,6 +1,8 @@
 import * as fs from "fs";
 import * as path from "path";
 
+import * as semver from "semver";
+
 import { getApiClient } from "./api-client";
 import { CodeQL } from "./codeql";
 import * as defaults from "./defaults.json"; // Referenced from codeql-action-sync-tool!
@@ -179,19 +181,27 @@ class GitHubFeatureFlags implements FeatureEnablement {
     /**/
   }
 
-  private static getCliVersionFromFeatureFlag(f: string): string | undefined {
+  private getCliVersionFromFeatureFlag(f: string): string | undefined {
     if (
       !f.startsWith(DEFAULT_VERSION_FEATURE_FLAG_PREFIX) ||
       !f.endsWith(DEFAULT_VERSION_FEATURE_FLAG_SUFFIX)
     ) {
       return undefined;
     }
-    return f
+    const version = f
       .substring(
         DEFAULT_VERSION_FEATURE_FLAG_PREFIX.length,
         f.length - DEFAULT_VERSION_FEATURE_FLAG_SUFFIX.length
       )
       .replace(/_/g, ".");
+
+    if (!semver.valid(version)) {
+      this.logger.warning(
+        `Ignoring feature flag ${f} as it does not specify a valid CodeQL version.`
+      );
+      return undefined;
+    }
+    return version;
   }
 
   async getDefaultCliVersion(
@@ -215,9 +225,7 @@ class GitHubFeatureFlags implements FeatureEnablement {
 
     const enabledFeatureFlagCliVersions = Object.entries(response)
       .map(([f, isEnabled]) =>
-        isEnabled
-          ? GitHubFeatureFlags.getCliVersionFromFeatureFlag(f)
-          : undefined
+        isEnabled ? this.getCliVersionFromFeatureFlag(f) : undefined
       )
       .filter((f) => f !== undefined)
       .map((f) => f as string);