fix: allow (but deprecate) use of old preprocessor.js

preprocessor.js

@@ -0,0 +1,7 @@
+console.warn(
+  `[ts-jest][DEPRECATED] - replace any occurrences to "ts-jest/dist/preprocessor.js" or ` +
+    ` "<rootDir>/node_modules/ts-jest/preprocessor.js"` +
+    ` in the 'transform' section of your Jest config with just "ts-jest".`
+);
+
+module.exports = require('./dist');

scripts/tests.js

@@ -39,6 +39,13 @@ function createIntegrationMock() {
       path.resolve(testCaseModuleFolder, 'package.json')
     );
 
+    // TODO: remove this in next major version as well as the test, and the preprocessor.js file in root
+    // Copy preprocessor.js
+    fs.copySync(
+      path.resolve(rootDir, 'preprocessor.js'),
+      path.resolve(testCaseModuleFolder, 'preprocessor.js')
+    );
+
     // Copy dist folder
     fs.copySync(
       path.resolve(rootDir, 'dist'),

tests/__tests__/__snapshots__/deprecated-transform.spec.ts.snap

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Deprecated Jest transform value should log the depration message 1`] = `"[ts-jest][DEPRECATED] - replace any occurrences to \\"ts-jest/dist/preprocessor.js\\" or  \\"<rootDir>/node_modules/ts-jest/preprocessor.js\\" in the 'transform' section of your Jest config with just \\"ts-jest\\"."`;

tests/__tests__/deprecated-transform.spec.ts

@@ -0,0 +1,14 @@
+import runJest from '../__helpers__/runJest';
+
+describe('Deprecated Jest transform value', () => {
+  it('should log the depration message', () => {
+    const result = runJest('../deprecated-transform', ['--no-cache']);
+
+    const output = result.stderr;
+
+    // get only the line with deprecation message (we dont want the snapshot to contain any timing or test name)
+    const msg = output.split('\n').find(line => /deprecated/i.test(line));
+
+    expect(msg).toMatchSnapshot();
+  });
+});

tests/deprecated-transform/Hello.ts

@@ -0,0 +1,3 @@
+export class Hello {
+  constructor(readonly msg: string) {}
+}

tests/deprecated-transform/__tests__/Hello.test.ts

@@ -0,0 +1,10 @@
+declare var jest, describe, it, expect;
+
+import { Hello } from '../Hello';
+
+describe('Hello Class', () => {
+  it('should create a new Hello', () => {
+    const hello = new Hello('foo');
+    expect(hello.msg).toBe('foo');
+  });
+});

tests/deprecated-transform/package.json

@@ -0,0 +1,9 @@
+{
+  "jest": {
+    "transform": {
+      "^.+\\.tsx?$": "<rootDir>/node_modules/ts-jest/preprocessor.js"
+    },
+    "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)$",
+    "moduleFileExtensions": ["ts", "js"]
+  }
+}

tests/deprecated-transform/tsconfig.json

@@ -0,0 +1,5 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+  }
+}