fix(utils): revert path.join and add check on prefix ends with / (#1989)

Closes #1982

Author: ahnpnl

e2e/__cases__/utils/src/foo/bar.ts

@@ -1,13 +1,8 @@
 import * as utils from 'ts-jest/utils'
-import { compilerOptions } from './tsconfig.json';
 
 test('utils', () => {
   expect(Object.keys(utils)).toEqual(['mocked', 'createJestPreset', 'pathsToModuleNameMapper'])
   expect(typeof utils.mocked).toBe('function')
   expect(typeof utils.createJestPreset).toBe('function')
   expect(typeof utils.pathsToModuleNameMapper).toBe('function')
 })
-
-test('pathsToModuleNameMapper', () => {
-  expect(utils.pathsToModuleNameMapper(compilerOptions.paths, { prefix: compilerOptions.baseUrl } )).toEqual({'^foo/(.*)$': 'src/foo/$1'})
-})

e2e/__cases__/utils/ts-jest-utils.spec.ts

@@ -2,6 +2,7 @@
 
 exports[`pathsToModuleNameMapper should convert tsconfig mapping with given prefix: <rootDir>/ 1`] = `
 Object {
+  "^@foo\\\\-bar/common$": "<rootDir>/../common/dist/library",
   "^api/(.*)$": "<rootDir>/src/api/$1",
   "^client$": Array [
     "<rootDir>/src/client",
@@ -21,6 +22,7 @@ Object {
 
 exports[`pathsToModuleNameMapper should convert tsconfig mapping with given prefix: foo 1`] = `
 Object {
+  "^@foo\\\\-bar/common$": "foo/../common/dist/library",
   "^api/(.*)$": "foo/src/api/$1",
   "^client$": Array [
     "foo/src/client",

e2e/__cases__/utils/tsconfig.json

@@ -11,12 +11,14 @@ const tsconfigMap = {
   'test/*': ['test/*'],
   'mocks/*': ['test/mocks/*'],
   'test/*/mock': ['test/mocks/*', 'test/__mocks__/*'],
+  '@foo-bar/common': ['../common/dist/library'],
 }
 
 describe('pathsToModuleNameMapper', () => {
   it('should convert tsconfig mapping with no given prefix', () => {
     expect(pathsToModuleNameMapper(tsconfigMap)).toMatchInlineSnapshot(`
       Object {
+        "^@foo\\\\-bar/common$": "../common/dist/library",
         "^api/(.*)$": "src/api/$1",
         "^client$": Array [
           "src/client",

src/config/__snapshots__/paths-to-module-name-mapper.spec.ts.snap

@@ -4,8 +4,6 @@ import type { CompilerOptions } from 'typescript'
 
 import { rootLogger } from '../utils/logger'
 import { Errors, interpolate } from '../utils/messages'
-import { join } from 'path'
-import { normalizeSlashes } from '../utils/normalize-slashes'
 
 type TsPathMapping = Exclude<CompilerOptions['paths'], undefined>
 type JestPathMapping = Config.InitialOptions['moduleNameMapper']
@@ -18,7 +16,7 @@ const logger = rootLogger.child({ [LogContexts.namespace]: 'path-mapper' })
 
 export const pathsToModuleNameMapper = (
   mapping: TsPathMapping,
-  { prefix = '' }: { prefix?: string } = {},
+  { prefix = '' }: { prefix: string } = Object.create(null),
 ): JestPathMapping => {
   const jestMap: JestPathMapping = {}
   for (const fromPath of Object.keys(mapping)) {
@@ -34,11 +32,19 @@ export const pathsToModuleNameMapper = (
     // split with '*'
     const segments = fromPath.split(/\*/g)
     if (segments.length === 1) {
-      const paths = toPaths.map((target) => normalizeSlashes(join(prefix, target)))
+      const paths = toPaths.map((target) => {
+        const enrichedPrefix = prefix !== '' && !prefix.endsWith('/') ? `${prefix}/` : prefix
+
+        return `${enrichedPrefix}${target}`
+      })
       pattern = `^${escapeRegex(fromPath)}$`
       jestMap[pattern] = paths.length === 1 ? paths[0] : paths
     } else if (segments.length === 2) {
-      const paths = toPaths.map((target) => normalizeSlashes(join(prefix, target.replace(/\*/g, '$1'))))
+      const paths = toPaths.map((target) => {
+        const enrichedPrefix = prefix !== '' && !prefix.endsWith('/') ? `${prefix}/` : prefix
+
+        return `${enrichedPrefix}${target.replace(/\*/g, '$1')}`
+      })
       pattern = `^${escapeRegex(segments[0])}(.*)${escapeRegex(segments[1])}$`
       jestMap[pattern] = paths.length === 1 ? paths[0] : paths
     } else {