chore(coverage): migrate from istanbul to c8 ignore comments

Replace all instances of istanbul ignore comments with c8 ignore syntax across
multiple files in the codebase. This change maintains the same code coverage
exclusions while updating to the newer c8 coverage tool format.

The changes include:
- Converting single-line ignores to c8 ignore start/stop blocks
- Updating existing ignore comments to maintain their original purpose
- Preserving the explanatory comments for why certain sections are ignored

Author: mrgrain

packages/@aws-cdk/tmp-toolkit-helpers/src/util/directories.ts

@@ -20,10 +20,11 @@ export function cdkHomeDir() {
   try {
     let userInfoHome: string | undefined = os.userInfo().homedir;
     // Node returns this if the user doesn't have a home directory
-    /* istanbul ignore if: will not happen in normal setups */
+    /* c8 ignore start */ // will not happen in normal setups
     if (userInfoHome == '/var/empty') {
       userInfoHome = undefined;
     }
+    /* c8 ignore stop */
     home = path.join((userInfoHome ?? os.homedir()).trim(), '.cdk');
   } catch {
   }

packages/@aws-cdk/tmp-toolkit-helpers/src/util/type-brands.ts

@@ -37,9 +37,10 @@ export type Branded<T, B> = T & Brand<B>;
  * values which are branded by construction (really just an elaborate
  * way to write 'as').
  */
-/* c8 ignore next 3 */
+/* c8 ignore start */
 export function createBranded<A extends Branded<any, any>>(value: TypeUnderlyingBrand<A>): A {
   return value as A;
 }
+/* c8 ignore stop */
 
 type TypeUnderlyingBrand<A> = A extends Branded<infer T, any> ? T : never;

packages/aws-cdk/lib/api/logs/logs-monitor.ts

@@ -146,10 +146,11 @@ export class CloudWatchLogEventMonitor {
   private async tick(): Promise<void> {
     // excluding from codecoverage because this
     // doesn't always run (depends on timing)
-    /* c8 ignore next */
+    /* c8 ignore start */
     if (!this.monitorId) {
       return;
     }
+    /* c8 ignore stop */
 
     try {
       const events = flatten(await this.readNewEvents());

packages/aws-cdk/lib/api/util/rwlock.ts

@@ -12,7 +12,7 @@ import { ToolkitError } from '../../../../@aws-cdk/tmp-toolkit-helpers/src/api';
  * This class is not 100% race safe, but in practice it should be a lot
  * better than the 0 protection we have today.
  */
-/* istanbul ignore next: code paths are unpredictable */
+/* c8 ignore start */ // code paths are unpredictable
 export class RWLock {
   private readonly pidString: string;
   private readonly writerFile: string;
@@ -146,6 +146,7 @@ export class RWLock {
     return ret;
   }
 }
+/* c8 ignore stop */
 
 /**
  * An acquired lock
@@ -164,7 +165,7 @@ export interface IWriterLock extends ILock {
   convertToReaderLock(): Promise<ILock>;
 }
 
-/* istanbul ignore next: code paths are unpredictable */
+/* c8 ignore start */ // code paths are unpredictable
 async function readFileIfExists(filename: string): Promise<string | undefined> {
   try {
     return await fs.readFile(filename, { encoding: 'utf-8' });
@@ -175,17 +176,19 @@ async function readFileIfExists(filename: string): Promise<string | undefined> {
     throw e;
   }
 }
+/* c8 ignore stop */
 
 let tmpCounter = 0;
-/* istanbul ignore next: code paths are unpredictable */
+/* c8 ignore start */ // code paths are unpredictable
 async function writeFileAtomic(filename: string, contents: string): Promise<void> {
   await fs.mkdir(path.dirname(filename), { recursive: true });
   const tmpFile = `${filename}.${process.pid}_${++tmpCounter}`;
   await fs.writeFile(tmpFile, contents, { encoding: 'utf-8' });
   await fs.rename(tmpFile, filename);
 }
+/* c8 ignore stop */
 
-/* istanbul ignore next: code paths are unpredictable */
+/* c8 ignore start */ // code paths are unpredictable
 async function deleteFile(filename: string) {
   try {
     await fs.unlink(filename);
@@ -196,8 +199,9 @@ async function deleteFile(filename: string) {
     throw e;
   }
 }
+/* c8 ignore stop */
 
-/* istanbul ignore next: code paths are unpredictable */
+/* c8 ignore start */ // code paths are unpredictable
 function processExists(pid: number) {
   try {
     process.kill(pid, 0);
@@ -206,3 +210,4 @@ function processExists(pid: number) {
     return false;
   }
 }
+/* c8 ignore stop */

packages/aws-cdk/lib/cli/cli.ts

@@ -595,7 +595,7 @@ function determineHotswapMode(hotswap?: boolean, hotswapFallback?: boolean, watc
   return hotswapMode;
 }
 
-/* istanbul ignore next: we never call this in unit tests */
+/* c8 ignore start */ // we never call this in unit tests
 export function cli(args: string[] = process.argv.slice(2)) {
   exec(args)
     .then(async (value) => {
@@ -610,3 +610,4 @@ export function cli(args: string[] = process.argv.slice(2)) {
       process.exitCode = 1;
     });
 }
+/* c8 ignore stop */

packages/aws-cdk/lib/cli/pretty-print-error.ts

@@ -1,6 +1,7 @@
 /* eslint-disable no-console */
 import * as chalk from 'chalk';
 
+/* c8 ignore start */
 export function prettyPrintError(error: unknown, debug = false) {
   const err = ensureError(error);
   console.error(chalk.red(err.message));
@@ -34,3 +35,4 @@ function ensureError(value: unknown): Error {
   const error = new Error(`An unexpected error was thrown: ${stringified}`);
   return error;
 }
+/* c8 ignore stop */

packages/aws-cdk/lib/cli/util/npm.ts

@@ -6,7 +6,7 @@ import { debug } from '../../logging';
 
 const exec = promisify(_exec);
 
-/* istanbul ignore next: not called during unit tests */
+/* c8 ignore start */ // not called during unit tests
 export async function getLatestVersionFromNpm(): Promise<string> {
   const { stdout, stderr } = await exec('npm view aws-cdk version', { timeout: 3000 });
   if (stderr && stderr.trim().length > 0) {
@@ -19,3 +19,4 @@ export async function getLatestVersionFromNpm(): Promise<string> {
 
   return latestVersion;
 }
+/* c8 ignore stop */

packages/aws-cdk/lib/cli/version.ts

@@ -1,4 +1,4 @@
-/* istanbul ignore file */
+/* c8 ignore start */
 import * as path from 'path';
 import * as chalk from 'chalk';
 import * as fs from 'fs-extra';
@@ -130,3 +130,4 @@ export async function displayVersionMessage(currentVersion = versionNumber(), ve
     debug(`Could not run version check - ${err.message}`);
   }
 }
+/* c8 ignore stop */

packages/aws-cdk/lib/commands/context.ts

@@ -56,9 +56,10 @@ export async function contextHandler(options: ContextOptions): Promise<number> {
   } else {
     // List -- support '--json' flag
     if (options.json) {
-      /* istanbul ignore next */
+      /* c8 ignore start */
       const contextValues = options.context.all;
       result(JSON.stringify(contextValues, undefined, 2));
+      /* c8 ignore stop */
     } else {
       listContext(options.context);
     }

packages/aws-cdk/lib/commands/init/init.ts

@@ -509,10 +509,11 @@ async function loadInitVersions(): Promise<Versions> {
     'aws-cdk': versionNumber(),
   };
   for (const [key, value] of Object.entries(ret)) {
-    /* istanbul ignore next */
+    /* c8 ignore start */
     if (!value) {
       throw new ToolkitError(`Missing init version from ${initVersionFile}: ${key}`);
     }
+    /* c8 ignore stop */
   }
 
   return ret;