Add first class Javascript/Typescript support to the Mill build tool (#…

…4098)

#3927

### Checklist
- [x] **example/jslib/testing**
    - [x] 1-test-suite
    - [x] 2-test-deps

example/javascriptlib/basic/1-simple/build.mill

@@ -2,9 +2,9 @@ package build
 
 import mill._, javascriptlib._
 
-object foo extends JestModule {
+object foo extends TypeScriptModule {
   def npmDeps = Seq("[email protected]")
-
+  object test extends TypeScriptTests with TestModule.Jest
 }
 
 // Documentation for mill.example.javascriptlib
@@ -15,16 +15,10 @@ Hello James Bond Professor
 
 > mill foo.test
 PASS .../foo.test.ts
-...generateUser function
-...should generate a user with all specified fields...
-...should default lastName and role when they are not provided...
-...should default all fields when args is empty...
 ...
 Test Suites:...1 passed, 1 total...
 Tests:...3 passed, 3 total...
-Snapshots:...
-Time:...
-Ran all test suites matching ...
+...
 
 > mill show foo.bundle
 Build succeeded!

example/javascriptlib/basic/1-simple/foo/test/foo.test.ts → example/javascriptlib/basic/1-simple/foo/test/src/foo/foo.test.ts

@@ -1,4 +1,4 @@
-import {generateUser, defaultRoles} from "../src/foo";
+import {generateUser, defaultRoles} from "foo/foo";
 import {Map} from 'node_modules/immutable';
 
 // Define the type roles object

example/javascriptlib/basic/1-simple/jest.config.ts

@@ -1,13 +1,32 @@
+// @ts-nocheck
+import {pathsToModuleNameMapper} from 'node_modules/ts-jest';
+import {compilerOptions} from './tsconfig.json'; // this is a generated file.
+
+// Remove unwanted keys
+const moduleDeps = {...compilerOptions.paths};
+delete moduleDeps['*'];
+delete moduleDeps['typeRoots'];
+
+// moduleNameMapper evaluates in order they appear,
+// sortedModuleDeps makes sure more specific path mappings always appear first
+const sortedModuleDeps = Object.keys(moduleDeps)
+    .sort((a, b) => b.length - a.length) // Sort by descending length
+    .reduce((acc, key) => {
+        acc[key] = moduleDeps[key];
+        return acc;
+    }, {});
+
 export default {
     preset: 'ts-jest',
     testEnvironment: 'node',
     testMatch: [
-        '<rootDir>/**/test/**/*.test.ts',
-        '<rootDir>/**/test/**/*.test.js',
+        '<rootDir>/**/**/**/*.test.ts',
+        '<rootDir>/**/**/**/*.test.js',
     ],
     transform: {
         '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: 'tsconfig.json' }],
         '^.+\\.(js|jsx)$': 'babel-jest', // Use babel-jest for JS/JSX files
     },
-    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node']
+    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+    moduleNameMapper: pathsToModuleNameMapper(sortedModuleDeps) // use absolute paths generated in tsconfig.
 };

example/javascriptlib/basic/3-custom-build-logic/build.mill

@@ -2,7 +2,7 @@ package build
 
 import mill._, javascriptlib._
 
-object foo extends JestModule {
+object foo extends TypeScriptModule {
 
   /** Total number of lines in module source files */
   def lineCount = Task {
@@ -20,6 +20,8 @@ object foo extends JestModule {
     super.mkENV() ++ Map("RESOURCE_PATH" -> resources().path.toString)
   }
 
+  object test extends TypeScriptTests with TestModule.Jest
+
 }
 
 // Documentation for mill.example.javascriptlib
@@ -28,15 +30,10 @@ object foo extends JestModule {
 
 > mill foo.test
 PASS .../foo.test.ts
-...Foo.getLineCount
-...should return the content of the line-count.txt file...
-...should return null if the file cannot be read...
 ...
 Test Suites:...1 passed, 1 total...
 Tests:...2 passed, 2 total...
-Snapshots:...
-Time:...
-Ran all test suites matching...
+...
 
 > mill foo.run
 [Reading file:] .../out/foo/resources.dest/line-count.txt

example/javascriptlib/basic/3-custom-build-logic/foo/test/foo.test.ts → example/javascriptlib/basic/3-custom-build-logic/foo/test/src/foo/foo.test.ts

@@ -1,6 +1,6 @@
 import * as fs from 'fs';
 import * as path from 'path';
-import Foo from '../src/foo';
+import Foo from 'foo/foo';
 
 // Mock the 'fs' module
 jest.mock('fs');

example/javascriptlib/basic/3-custom-build-logic/jest.config.ts

@@ -1,14 +1,32 @@
+// @ts-nocheck
+import {pathsToModuleNameMapper} from 'node_modules/ts-jest';
+import {compilerOptions} from './tsconfig.json'; // this is a generated file.
+
+// Remove unwanted keys
+const moduleDeps = {...compilerOptions.paths};
+delete moduleDeps['*'];
+delete moduleDeps['typeRoots'];
+
+// moduleNameMapper evaluates in order they appear,
+// sortedModuleDeps makes sure more specific path mappings always appear first
+const sortedModuleDeps = Object.keys(moduleDeps)
+    .sort((a, b) => b.length - a.length) // Sort by descending length
+    .reduce((acc, key) => {
+        acc[key] = moduleDeps[key];
+        return acc;
+    }, {});
+
 export default {
     preset: 'ts-jest',
     testEnvironment: 'node',
     testMatch: [
-        '<rootDir>/**/test/**/*.test.ts',
-        '<rootDir>/**/test/**/*.test.js',
+        '<rootDir>/**/**/**/*.test.ts',
+        '<rootDir>/**/**/**/*.test.js',
     ],
     transform: {
-        '^.+\\.(ts|tsx)$': ['ts-jest', {tsconfig: 'tsconfig.json'}],
-        '^.+\\.(js|jsx)$': 'babel-jest',
+        '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: 'tsconfig.json' }],
+        '^.+\\.(js|jsx)$': 'babel-jest', // Use babel-jest for JS/JSX files
     },
     moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
-    moduleNameMapper: {}
+    moduleNameMapper: pathsToModuleNameMapper(sortedModuleDeps) // use absolute paths generated in tsconfig.
 };

example/javascriptlib/basic/4-multi-modules/build.mill

@@ -9,8 +9,9 @@ object foo extends TypeScriptModule {
 
 }
 
-object qux extends JestModule {
+object qux extends TypeScriptModule {
   def moduleDeps = Seq(foo, foo.bar)
+  object test extends TypeScriptTests with TestModule.Jest
 }
 
 // Documentation for mill.example.javascriptlib

example/javascriptlib/basic/4-multi-modules/jest.config.ts

@@ -20,8 +20,8 @@ export default {
     preset: 'ts-jest',
     testEnvironment: 'node',
     testMatch: [
-        '<rootDir>/**/test/**/*.test.ts',
-        '<rootDir>/**/test/**/*.test.js',
+        '<rootDir>/**/**/**/*.test.ts',
+        '<rootDir>/**/**/**/*.test.js',
     ],
     transform: {
         '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: 'tsconfig.json' }],

example/javascriptlib/basic/4-multi-modules/qux/test/qux.test.ts → example/javascriptlib/basic/4-multi-modules/qux/test/src/qux/qux.test.ts

@@ -1,4 +1,4 @@
-import { generateUser } from "../src/qux";
+import { generateUser } from "qux/qux";
 
 // Define the type roles object
 type RoleKeys = "admin" | "user";

example/javascriptlib/basic/5-client-server-hello/build.mill

@@ -3,7 +3,7 @@ import mill._, javascriptlib._
 
 object client extends ReactScriptsModule
 
-object server extends JestModule {
+object server extends TypeScriptModule {
   override def mkENV = Task {
     super.mkENV() ++ Map("PORT" -> "3000")
   }
@@ -13,6 +13,8 @@ object server extends JestModule {
     os.copy(clientBundle, Task.dest / "build")
     PathRef(Task.dest)
   }
+
+  object test extends TypeScriptTests with TestModule.Jest
 }
 
 // Documentation for mill.example.javascriptlib
@@ -33,6 +35,9 @@ PASS .../App.test.tsx
 ...
 PASS .../server.test.ts
 ...
+Test Suites:...1 passed, 1 total...
+Tests:...1 passed, 1 total...
+...
 
 > mill show server.bundle # bundle the express server
 Build succeeded!

example/javascriptlib/basic/5-client-server-hello/jest.config.ts

@@ -1,13 +1,32 @@
+// @ts-nocheck
+import {pathsToModuleNameMapper} from 'node_modules/ts-jest';
+import {compilerOptions} from './tsconfig.json'; // this is a generated file.
+
+// Remove unwanted keys
+const moduleDeps = {...compilerOptions.paths};
+delete moduleDeps['*'];
+delete moduleDeps['typeRoots'];
+
+// moduleNameMapper evaluates in order they appear,
+// sortedModuleDeps makes sure more specific path mappings always appear first
+const sortedModuleDeps = Object.keys(moduleDeps)
+    .sort((a, b) => b.length - a.length) // Sort by descending length
+    .reduce((acc, key) => {
+        acc[key] = moduleDeps[key];
+        return acc;
+    }, {});
+
 export default {
     preset: 'ts-jest',
     testEnvironment: 'node',
     testMatch: [
-        '<rootDir>/**/test/**/*.test.ts',
-        '<rootDir>/**/test/**/*.test.js',
+        '<rootDir>/**/**/**/*.test.ts',
+        '<rootDir>/**/**/**/*.test.js',
     ],
     transform: {
-        '^.+\\.(ts|tsx)$': ['ts-jest', {tsconfig: 'tsconfig.json'}],
+        '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: 'tsconfig.json' }],
         '^.+\\.(js|jsx)$': 'babel-jest', // Use babel-jest for JS/JSX files
     },
     moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+    moduleNameMapper: pathsToModuleNameMapper(sortedModuleDeps) // use absolute paths generated in tsconfig.
 };

example/javascriptlib/basic/5-client-server-hello/server/test/server.test.ts → example/javascriptlib/basic/5-client-server-hello/server/test/src/server/server.test.ts

@@ -4,7 +4,7 @@ describe('Server Tests', () => {
     let server: http.Server;
 
     beforeAll(() => {
-        server = require('../src/server').default;
+        server = require('server/server').default;
         process.env.NODE_ENV = "test";
     });
 

example/javascriptlib/basic/6-client-server-realistic/build.mill

@@ -3,15 +3,13 @@ import mill._, javascriptlib._
 
 object client extends ReactScriptsModule
 
-object server extends JestModule {
+object server extends TypeScriptModule {
   def npmDeps =
     Seq("@types/cors@^2.8.17", "@types/express@^5.0.0", "cors@^2.8.5", "express@^4.21.1")
 
   def npmDevDeps =
     super.npmDevDeps() ++ Seq("@types/supertest@^6.0.2", "supertest@^7.0.0")
 
-  override def testConfigSource = Task.Source(millSourcePath / "jest.config.ts")
-
   override def bundleFlags = Map("external" -> Seq("express", "cors"))
 
   override def mkENV = Task {
@@ -23,6 +21,10 @@ object server extends JestModule {
     os.copy(clientBundle, Task.dest / "build")
     PathRef(Task.dest)
   }
+
+  object test extends TypeScriptTests with TestModule.Jest {
+    override def testConfigSource = Task.Source(millSourcePath / os.up / "jest.config.ts")
+  }
 }
 
 // Documentation for mill.example.javascriptlib
@@ -37,6 +39,9 @@ object server extends JestModule {
 > mill server.test
 PASS .../server.test.ts
 ...
+Test Suites:...1 passed, 1 total...
+Tests:...3 passed, 3 total...
+...
 
 > mill show server.bundle # bundle the express server
 Build succeeded!

example/javascriptlib/basic/6-client-server-realistic/server/jest.config.ts

@@ -1,13 +1,32 @@
+// @ts-nocheck
+import {pathsToModuleNameMapper} from 'node_modules/ts-jest';
+import {compilerOptions} from './tsconfig.json'; // this is a generated file.
+
+// Remove unwanted keys
+const moduleDeps = {...compilerOptions.paths};
+delete moduleDeps['*'];
+delete moduleDeps['typeRoots'];
+
+// moduleNameMapper evaluates in order they appear,
+// sortedModuleDeps makes sure more specific path mappings always appear first
+const sortedModuleDeps = Object.keys(moduleDeps)
+    .sort((a, b) => b.length - a.length) // Sort by descending length
+    .reduce((acc, key) => {
+        acc[key] = moduleDeps[key];
+        return acc;
+    }, {});
+
 export default {
     preset: 'ts-jest',
     testEnvironment: 'node',
     testMatch: [
-        '<rootDir>/**/test/**/*.test.ts',
-        '<rootDir>/**/test/**/*.test.js',
+        '<rootDir>/**/**/**/*.test.ts',
+        '<rootDir>/**/**/**/*.test.js',
     ],
     transform: {
-        '^.+\\.(ts|tsx)$': ['ts-jest', {tsconfig: 'tsconfig.json'}],
+        '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: 'tsconfig.json' }],
         '^.+\\.(js|jsx)$': 'babel-jest', // Use babel-jest for JS/JSX files
     },
-    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node']
+    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+    moduleNameMapper: pathsToModuleNameMapper(sortedModuleDeps) // use absolute paths generated in tsconfig.
 };

example/javascriptlib/basic/6-client-server-realistic/server/test/server.test.ts → example/javascriptlib/basic/6-client-server-realistic/server/test/src/server/server.test.ts

@@ -9,7 +9,7 @@ describe('Server Tests', () => {
     beforeAll((done) => {
         process.env.PORT = '3002';
         process.env.NODE_ENV = 'test';
-        app = require('../src/server').default;
+        app = require('server/server').default;
         server = app.listen(process.env.PORT, done);
     });
 

example/javascriptlib/testing/1-test-suite/bar/src/calculator.ts

@@ -0,0 +1,12 @@
+export class Calculator {
+    add(a: number, b: number): number {
+        return a + b;
+    }
+
+    divide(a: number, b: number): number {
+        if (b === 0) {
+            throw new Error("Division by zero is not allowed");
+        }
+        return a / b;
+    }
+}

example/javascriptlib/testing/1-test-suite/bar/test/src/bar/calculator.test.ts

@@ -0,0 +1,28 @@
+import {Calculator} from 'bar/calculator';
+
+describe('Calculator', () => {
+    const calculator = new Calculator();
+
+    describe('Addition', () => {
+        test('should return the sum of two numbers', () => {
+            const result = calculator.add(2, 3);
+            expect(result).toEqual(5);
+        });
+
+        test('should return the correct sum for negative numbers', () => {
+            const result = calculator.add(-2, -3);
+            expect(result).toEqual(-5);
+        });
+    });
+
+    describe('Division', () => {
+        test('should return the quotient of two numbers', () => {
+            const result = calculator.divide(6, 3);
+            expect(result).toEqual(2);
+        });
+
+        it('should throw an error when dividing by zero', () => {
+            expect(() => calculator.divide(6, 0)).toThrow("Division by zero is not allowed");
+        });
+    });
+});