Add test to ensure overlay-base cache keys are stable

Author: kaspersv

src/overlay-database-utils.test.ts

@@ -14,6 +14,8 @@ import {
   OverlayDatabaseMode,
   writeBaseDatabaseOidsFile,
   writeOverlayChangesFile,
+  getCacheRestoreKeyPrefix,
+  getCacheSaveKey,
 } from "./overlay-database-utils";
 import {
   createTestConfig,
@@ -261,3 +263,37 @@ test(
   },
   false,
 );
+
+test("overlay-base database cache keys remain stable", async (t) => {
+  const config = createTestConfig({ languages: ["python", "javascript"] });
+  const codeQlVersion = "2.23.0";
+  const commitOid = "abc123def456";
+  sinon.stub(apiClient, "getAutomationID").resolves("test-automation-id/");
+  sinon.stub(gitUtils, "getCommitOid").resolves(commitOid);
+  const saveKey = await getCacheSaveKey(config, codeQlVersion, "checkout-path");
+  const expectedSaveKey =
+    "codeql-overlay-base-database-1-c5666c509a2d9895-javascript_python-2.23.0-abc123def456";
+  t.is(
+    saveKey,
+    expectedSaveKey,
+    "Cache save key changed unexpectedly. " +
+      "This may indicate breaking changes in the cache key generation logic.",
+  );
+  const restoreKeyPrefix = await getCacheRestoreKeyPrefix(
+    config,
+    codeQlVersion,
+  );
+  const expectedRestoreKeyPrefix =
+    "codeql-overlay-base-database-1-c5666c509a2d9895-javascript_python-2.23.0-";
+  t.is(
+    restoreKeyPrefix,
+    expectedRestoreKeyPrefix,
+    "Cache restore key prefix changed unexpectedly. " +
+      "This may indicate breaking changes in the cache key generation logic.",
+  );
+
+  t.true(
+    saveKey.startsWith(restoreKeyPrefix),
+    `Expected save key "${saveKey}" to start with restore key prefix "${restoreKeyPrefix}"`,
+  );
+});

src/overlay-database-utils.ts

@@ -448,7 +448,7 @@ export async function downloadOverlayBaseDatabaseFromCache(
  * The key consists of the restore key prefix (which does not include the
  * commit SHA) and the commit SHA of the current checkout.
  */
-async function getCacheSaveKey(
+export async function getCacheSaveKey(
   config: Config,
   codeQlVersion: string,
   checkoutPath: string,
@@ -475,7 +475,7 @@ async function getCacheSaveKey(
  * not include the commit SHA. This allows us to restore the most recent
  * compatible overlay-base database.
  */
-async function getCacheRestoreKeyPrefix(
+export async function getCacheRestoreKeyPrefix(
   config: Config,
   codeQlVersion: string,
 ): Promise<string> {