tests: add end to end deletion test

packages/e2e-tests/test/e2e.spec.ts

@@ -1674,8 +1674,9 @@ describe('e2e', function () {
           });
         });
 
-        /** Helper to visualize the existence of files, 1 if it exists, 0 otherwise. */
-        const existingFiles = async (paths: string[]) => {
+        /** Helper to visualize and compare the existence of files in a specific order.
+         * Returns a string comprised of: 1 if a given file exists, 0 otherwise. */
+        const getFilesState = async (paths: string[]) => {
           return (
             await Promise.all(
               paths.map((path) =>
@@ -1722,7 +1723,7 @@ describe('e2e', function () {
               `mongosh:\n  logLocation: "${customLogDir.path}"\n  logRetentionDays: ${retentionDays}`
             );
 
-            expect(await existingFiles(paths)).equals('1111111111');
+            expect(await getFilesState(paths)).equals('1111111111');
 
             shell = this.startTestShell({
               args: ['--nodb'],
@@ -1738,7 +1739,57 @@ describe('e2e', function () {
             // Add the newly created log file
             paths.push(path.join(customLogDir.path, `${shell.logId}_log`));
             // Expect 6 files to be deleted and 5 to remain (including the new log file)
-            expect(await existingFiles(paths)).equals('00000011111');
+            expect(await getFilesState(paths)).equals('00000011111');
+          });
+        });
+
+        describe('with custom log retention max file count', function () {
+          const customLogDir = useTmpdir();
+
+          it('should delete files once it is above the max file limit', async function () {
+            const globalConfig = path.join(homedir, 'globalconfig.conf');
+            await fs.writeFile(
+              globalConfig,
+              `mongosh:\n  logLocation: "${customLogDir.path}"\n  logMaxFileCount: 4`
+            );
+            const paths: string[] = [];
+            const offset = Math.floor(Date.now() / 1000);
+
+            // Create 10 log files
+            for (let i = 9; i >= 0; i--) {
+              const filename = path.join(
+                customLogDir.path,
+                ObjectId.createFromTime(offset - i).toHexString() + '_log'
+              );
+              await fs.writeFile(filename, '');
+              paths.push(filename);
+            }
+
+            // All 10 existing log files exist.
+            expect(await getFilesState(paths)).to.equal('1111111111');
+            shell = this.startTestShell({
+              args: ['--nodb'],
+              env: {
+                ...env,
+                MONGOSH_TEST_ONLY_MAX_LOG_FILE_COUNT: '',
+                MONGOSH_GLOBAL_CONFIG_FILE_FOR_TESTING: globalConfig,
+              },
+              forceTerminal: true,
+            });
+
+            await shell.waitForPrompt();
+
+            // Add the newly created log to the file list.
+            paths.push(
+              path.join(customLogDir.path, `${shell.logId as string}_log`)
+            );
+
+            expect(
+              await shell.executeLine('config.get("logMaxFileCount")')
+            ).contains('4');
+
+            // Expect 7 files to be deleted and 4 to remain (including the new log file)
+            expect(await getFilesState(paths)).to.equal('00000001111');
           });
         });