From 7e8ce24116354a94c3421cf3bb2a7904aed4270f Mon Sep 17 00:00:00 2001
From: Pete Bacon Darwin <pete@bacondarwin.com>
Date: Mon, 10 Feb 2020 09:12:53 +0000
Subject: [PATCH] refactor(compiler-cli): add `invalidateCaches` to
 `CachedFileSystem` (#35131)

This is needed by ngcc when reading volatile files that may
be changed by an external process (e.g. the lockfile).

PR Close #35131
---
 .../file_system/src/cached_file_system.ts     |  5 +++
 .../test/cached_file_system_spec.ts           | 33 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts b/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts
index 92030c58c7..25e9ff81de 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/src/cached_file_system.ts
@@ -28,6 +28,11 @@ export class CachedFileSystem implements FileSystem {
     return this.existsCache.get(path) !;
   }
 
+  invalidateCaches(path: AbsoluteFsPath) {
+    this.readFileCache.delete(path);
+    this.existsCache.delete(path);
+  }
+
   readFile(path: AbsoluteFsPath): string {
     if (!this.readFileCache.has(path)) {
       try {
diff --git a/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts b/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts
index 04610ddaa1..1f81b7c1e9 100644
--- a/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts
+++ b/packages/compiler-cli/src/ngtsc/file_system/test/cached_file_system_spec.ts
@@ -90,6 +90,39 @@ describe('CachedFileSystem', () => {
     });
   });
 
+  describe('invalidateCaches()', () => {
+    it('should use the delegate for `readFile()` if the path for the cached file has been invalidated',
+       () => {
+         spyOn(delegate, 'lstat').and.returnValue({isSymbolicLink: () => false});
+         const spy = spyOn(delegate, 'readFile').and.returnValue('Some contents');
+         fs.readFile(abcPath);  // Call once to fill the cache
+         spy.calls.reset();
+
+         expect(fs.readFile(abcPath)).toBe('Some contents');
+         expect(spy).not.toHaveBeenCalled();
+
+         fs.invalidateCaches(abcPath);
+
+         expect(fs.readFile(abcPath)).toBe('Some contents');
+         expect(spy).toHaveBeenCalledWith(abcPath);
+       });
+
+    it('should use the delegate `exists()` if the path for the cached file has been invalidated',
+       () => {
+         const spy = spyOn(delegate, 'exists').and.returnValue(true);
+         fs.exists(abcPath);  // Call once to fill the cache
+         spy.calls.reset();
+
+         expect(fs.exists(abcPath)).toBe(true);
+         expect(spy).not.toHaveBeenCalled();
+
+         fs.invalidateCaches(abcPath);
+
+         expect(fs.exists(abcPath)).toBe(true);
+         expect(spy).toHaveBeenCalledWith(abcPath);
+       });
+  });
+
   describe('writeFile()', () => {
     it('should call delegate', () => {
       const spy = spyOn(delegate, 'writeFile');