feat(config): specify package.json location (kulshekhar#823)

Updates loading of package.json to allow specifying of file location or
entire contents in addition to existing behavior.

src/config/config-set.spec.ts

@@ -1,5 +1,5 @@
 import { testing } from 'bs-logger'
-import { resolve } from 'path'
+import { join, resolve } from 'path'
 import ts, { Diagnostic, DiagnosticCategory, ModuleKind, ScriptTarget } from 'typescript'
 
 import * as _myModule from '..'
@@ -402,6 +402,20 @@ describe('readTsConfig', () => {
   })
 }) // readTsConfig
 
+describe('readPackageJson', () => {
+  it('should return inlined package definitiopn', () => {
+    const cs = createConfigSet({ tsJestConfig: { packageJson: { foo: 'bar' } } as any })
+    const packageJson = cs.projectPackageJson
+    expect(packageJson.foo).toEqual('bar')
+  })
+
+  it('should use given package.json path', () => {
+    const expected = require(join(__dirname, '..', '..', 'package.json'))
+    const cs = createConfigSet({ tsJestConfig: { packageJson: join(__dirname, '..', '..', 'package.json') } as any })
+    expect(cs.projectPackageJson).toEqual(expected)
+  })
+}) // readPackageJson
+
 describe('versions', () => {
   describe('without babel', () => {
     it('should return correct version map', () => {

src/config/config-set.ts

@@ -114,18 +114,38 @@ const toDiagnosticCodeList = (items: any, into: number[] = []): number[] => {
 export class ConfigSet {
   @Memoize()
   get projectPackageJson(): Record<string, any> {
+    const parsedConfig = this.jest
+    const { globals = {} } = parsedConfig as any
+    const options: TsJestGlobalOptions = { ...globals['ts-jest'] }
+
+    if (options.packageJson && typeof options.packageJson === 'string') {
+      const path = this.resolvePath(options.packageJson)
+      if (existsSync(path)) {
+        return require(path)
+      }
+      this.logger.warn(Errors.UnableToFindProjectRoot)
+      return {}
+    }
+
+    if (options.packageJson && typeof options.packageJson === 'object') {
+      return options.packageJson
+    }
+
     const tsJestRoot = resolve(__dirname, '..', '..')
     let pkgPath = resolve(tsJestRoot, '..', '..', 'package.json')
-    let exists = existsSync(pkgPath)
-    if (!exists) {
-      if (realpathSync(this.rootDir) === realpathSync(tsJestRoot)) {
-        pkgPath = resolve(tsJestRoot, 'package.json')
-        exists = true
-      } else {
-        this.logger.warn(Errors.UnableToFindProjectRoot)
+    if (existsSync(pkgPath)) {
+      return require(pkgPath)
+    }
+
+    if (realpathSync(this.rootDir) === realpathSync(tsJestRoot)) {
+      pkgPath = resolve(tsJestRoot, 'package.json')
+      if (existsSync(pkgPath)) {
+        return require(pkgPath)
       }
     }
-    return exists ? require(pkgPath) : {}
+
+    this.logger.warn(Errors.UnableToFindProjectRoot)
+    return {}
   }
 
   @Memoize()

src/types.ts

@@ -21,6 +21,14 @@ export interface TsJestGlobalOptions {
    */
   tsConfig?: boolean | string | CompilerOptions
 
+  /**
+   * packageJson. It can be:
+   *     - `true` (or `undefined`, it's the default): use default package.json file
+   *     - `path/to/package.json`: path to a specific package.json file (<rootDir> can be used)
+   *     - `{...}`: contents of a package.json
+   */
+  packageJson?: boolean | string | object
+
   /**
    * Whether to compile files as isolated modules (disables some features and type-checking, default to `false`):
    */