test(jest): 🚨 added cli mock for jest

packages/devmoji/__tests__/cli-tester.ts

@@ -0,0 +1,48 @@
+import { MockCli } from "../src/cli-tester"
+
+test("sync", () => {
+  const mockCli = new MockCli()
+  mockCli.test(() => {
+    console.log("test")
+  })
+  expect(mockCli.stdout?.data).toMatch(/test/)
+})
+
+test("stderr", () => {
+  const mockCli = new MockCli()
+  mockCli.test(() => {
+    console.error("test")
+  })
+  expect(mockCli.stderr?.data).toMatch(/test/)
+})
+
+test("sync2", () => {
+  const mockCli = new MockCli()
+  mockCli.test(() => {
+    console.log("test")
+  })
+  expect(mockCli.stdout?.data).toMatch(/test/)
+})
+
+test("async1", () => {
+  const mockCli = new MockCli()
+  mockCli.testAsync(async () => {
+    await new Promise(done => {
+      process.stdout.write("test")
+      done()
+    })
+  })
+  expect(mockCli.stdout?.data).toMatch(/test/)
+})
+
+test("async2", () => {
+  const mockCli = new MockCli()
+  mockCli.testAsync(async () => {
+    console.log("foo")
+    await new Promise(done => {
+      console.log("test")
+      done()
+    })
+  })
+  expect(mockCli.stdout?.data).toMatch(/foo/)
+})

packages/devmoji/src/cli-tester.ts

@@ -0,0 +1,74 @@
+import { Writable, WritableOptions } from "stream"
+import { StringDecoder } from "string_decoder"
+import { Console } from "console"
+
+class StringWritable extends Writable {
+  data = ""
+  decoder: StringDecoder
+  constructor(options?: WritableOptions) {
+    super(options)
+    this.decoder = new StringDecoder("utf-8")
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  _write(chunk: any, encoding: string, callback: () => void) {
+    this.data += this.decoder.write(chunk)
+    callback()
+  }
+
+  _destroy(err: Error, callback: () => void) {
+    this.data += this.decoder.end()
+    callback()
+  }
+}
+
+export class MockCli {
+  mocks: [Writable, Writable, Writable["write"]][] = []
+  stdout?: StringWritable
+  stderr?: StringWritable
+  console = global.console
+  // eslint-disable-next-line @typescript-eslint/unbound-method
+
+  mock(stream: Writable) {
+    const mock = new StringWritable()
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    this.mocks.push([mock, stream, stream.write])
+    // eslint-disable-next-line @typescript-eslint/unbound-method
+    stream.write = mock.write.bind(mock)
+    return mock
+  }
+
+  restore() {
+    for (const [mock, stream, write] of this.mocks) {
+      mock.destroy()
+      // eslint-disable-next-line @typescript-eslint/unbound-method
+      stream.write = write.bind(stream)
+    }
+    global.console = this.console
+  }
+
+  setup() {
+    this.stdout = this.mock(global.process.stdout)
+    this.stderr = this.mock(global.process.stderr)
+    this.console = global.console
+    global.console = new Console({ stdout: this.stdout, stderr: this.stderr })
+  }
+
+  test(func: () => void) {
+    try {
+      this.setup()
+      func()
+    } finally {
+      this.restore()
+    }
+  }
+
+  async testAsync<T>(func: () => Promise<T>) {
+    this.setup()
+    try {
+      await func()
+    } finally {
+      this.restore()
+    }
+  }
+}