fix(compiler): add file content empty string to compiler cache

e2e/__external-repos__/simple/with-dependency/package.json

@@ -1,6 +1,7 @@
 {
   "name": "with-dependency",
-  "version": "0.0.1",
+  "version": "0.0.0",
+  "license": "MIT",
   "scripts": {
     "test": "jest --no-cache"
   },

e2e/__external-repos__/simple/with-dependency/tsconfig.json

@@ -13,9 +13,7 @@
     "downlevelIteration": true,
     "strict": true,
     "moduleResolution": "node",
-    "esModuleInterop": true
-  },
-  "include": [
-    "./src"
-  ]
+    "esModuleInterop": true,
+    "noEmitOnError": true
+  }
 }

package.json

@@ -119,6 +119,7 @@
     "eslint-plugin-prettier": "latest",
     "execa": "latest",
     "fs-extra": "10.x",
+    "glob": "^7.1.7",
     "glob-gitignore": "latest",
     "husky": "4.x",
     "jest": "^27.0.0",

scripts/lib/paths.js

@@ -1,5 +1,7 @@
 const os = require('os')
 const path = require('path')
+const glob = require('glob')
+const fs = require('fs')
 
 const rootDir = path.resolve(__dirname, '..', '..')
 const cacheDir = path.join(rootDir, '.cache')
@@ -16,14 +18,11 @@ const e2eWorkDir = process.env.TS_JEST_E2E_WORKDIR
   : path.join(os.tmpdir(), '--ts-jest-temp-e2e--')
 const e2eWorkTemplatesDir = path.join(e2eWorkDir, '__templates__')
 const e2eWorkDirLink = path.join(e2eRootDir, '__workdir_synlink__')
-const projectsToRun = [
-  `${e2eExternalRepoDir}/custom-typings`,
-  `${e2eExternalRepoDir}/memory-usage`,
-  `${e2eExternalRepoDir}/path-mapping`,
-  `${e2eExternalRepoDir}/simple/with-dependency`,
-  `${e2eExternalRepoDir}/simple-project-references`,
-  `${e2eExternalRepoDir}/yarn-workspace-composite`,
-]
+const projectsToRun = glob
+  .sync(`${e2eExternalRepoDir}/*`)
+  .filter((e2ePath) => fs.lstatSync(e2ePath).isDirectory() && fs.existsSync(path.join(e2ePath, 'package.json')))
+  .sort()
+projectsToRun.push(`${e2eExternalRepoDir}/simple/with-dependency`)
 const rawCompilerOptionsFileName = path.join('src', 'raw-compiler-options.ts')
 const generatedPath = path.join(process.cwd(), rawCompilerOptionsFileName)
 

src/compiler/ts-compiler.spec.ts

@@ -3,12 +3,13 @@ import { basename, join, normalize } from 'path'
 
 import { DiagnosticCategory, EmitOutput, ModuleKind, ScriptTarget, TranspileOutput } from 'typescript'
 
-import { makeCompiler } from '../__helpers__/fakers'
+import { createConfigSet, makeCompiler } from '../__helpers__/fakers'
 import { mockFolder } from '../__helpers__/path'
 import type { DepGraphInfo } from '../types'
 import { Errors, interpolate } from '../utils/messages'
 
 import { updateOutput } from './compiler-utils'
+import { TsCompiler } from './ts-compiler'
 
 const baseTsJestConfig = { tsconfig: join(process.cwd(), 'tsconfig.spec.json') }
 
@@ -163,9 +164,12 @@ describe('TsCompiler', () => {
       const sourceMap = '{}'
 
       test.each([true, false])('should compile codes with useESM %p', (useESM) => {
-        const compiler = makeCompiler({
+        const configSet = createConfigSet({
           tsJestConfig: { ...baseTsJestConfig, useESM },
         })
+        const emptyFile = join(mockFolder, 'empty.ts')
+        configSet.parsedTsConfig.fileNames.push(emptyFile)
+        const compiler = new TsCompiler(configSet, new Map())
         // @ts-expect-error testing purpose
         compiler._languageService.getEmitOutput = jest.fn().mockReturnValueOnce({
           outputFiles: [{ text: sourceMap }, { text: jsOutput }],
@@ -193,6 +197,13 @@ describe('TsCompiler', () => {
         expect(esModuleInterop).toEqual(useESM ? true : esModuleInterop)
         expect(allowSyntheticDefaultImports).toEqual(useESM ? true : allowSyntheticDefaultImports)
         expect(output).toEqual(updateOutput(jsOutput, fileName, sourceMap))
+
+        // @ts-expect-error testing purpose
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        compiler._languageService!.getSemanticDiagnostics(fileName)
+
+        // @ts-expect-error testing purpose
+        expect(compiler._fileContentCache.has(emptyFile)).toBe(true)
       })
 
       test('should show a warning message and return original file content for non ts/tsx files if emitSkipped is true', () => {

src/compiler/ts-compiler.ts

@@ -266,15 +266,15 @@ export class TsCompiler implements TsCompilerInstance {
 
         this._logger.trace({ normalizedFileName, cacheHit: hit }, 'getScriptSnapshot():', 'cache', hit ? 'hit' : 'miss')
 
-        // Read contents from TypeScript memory cache.
+        // Read file content from either memory cache or Jest runtime cache or fallback to file system read
         if (!hit) {
           const fileContent =
             // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
             this._fileContentCache!.get(normalizedFileName) ??
             this._runtimeCacheFS.get(normalizedFileName) ??
             this._cachedReadFile?.(normalizedFileName) ??
             undefined
-          if (fileContent) {
+          if (fileContent !== undefined) {
             // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
             this._fileContentCache!.set(normalizedFileName, fileContent)
             // eslint-disable-next-line @typescript-eslint/no-non-null-assertion