Add tests for the input prompt

.editorconfig

@@ -7,5 +7,5 @@ charset = utf-8
 trim_trailing_whitespace = true
 insert_final_newline = true
 
-[*.md]
+[*test.mts, *.md]
 trim_trailing_whitespace = false

packages/input/README.md

@@ -26,7 +26,7 @@ const answer = await input({ message: 'Enter your name' });
 | ----------- | ----------------------------------------------------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | message     | `string`                                                    | yes      | The question to ask                                                                                                                                                                                                     |
 | default     | `string`                                                    | no       | Default value if no answer is provided (clear it by pressing backspace)                                                                                                                                                 |
-| transformer | `(string, { isFinal: boolean }) => string`                  | no       | Transform/Format the raw value entered by the user. Once the prompt is completed, `isFinal` will be `true`. This function is purely visual; to modify the answer, use the `filter` option.                              |
+| transformer | `(string, { isFinal: boolean }) => string`                  | no       | Transform/Format the raw value entered by the user. Once the prompt is completed, `isFinal` will be `true`. This function is purely visual, modify the answer in your code if needed.                              |
 | validate    | `string => boolean \| string \| Promise<string \| boolean>` | no       | On submit, validate the filtered answered content. When returning a string, it'll be used as the error message displayed to the user. Note: returning a rejected promise, we'll assume a code error happened and crash. |
 
 # License

packages/input/package.json

@@ -58,6 +58,10 @@
     "@inquirer/type": "^0.1.0",
     "chalk": "^5.2.0"
   },
+  "devDependencies": {
+    "@inquirer/testing": "^0.1.0",
+    "@jest/globals": "^29.5.0"
+  },
   "scripts": {
     "tsc": "yarn run clean && yarn run tsc:esm && yarn run tsc:cjs",
     "clean": "rm -rf dist",

packages/input/test.mts

@@ -0,0 +1,136 @@
+import { render } from '@inquirer/testing';
+import input from './src/index.mjs';
+
+describe('input prompt', () => {
+  it('handle simple use case', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'What is your name',
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name"`);
+
+    events.type('J');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name J"`);
+
+    events.type('ohn');
+    events.keypress('enter');
+
+    await expect(answer).resolves.toEqual('John');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name John"`);
+  });
+
+  it('handle transformer', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'What is your name',
+      transformer: (value, { isFinal }) => (isFinal ? 'Transformed' : `t+${value}`),
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name t+"`);
+
+    events.type('John');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name t+John"`);
+
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual('John');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name Transformed"`);
+  });
+
+  it('handle synchronous validation', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'Answer 2 ===',
+      validate: (answer) => answer === '2',
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? Answer 2 ==="`);
+
+    events.type('1');
+    expect(getScreen()).toMatchInlineSnapshot(`"? Answer 2 === 1"`);
+
+    events.keypress('enter');
+    await Promise.resolve();
+    expect(getScreen()).toMatchInlineSnapshot(`
+      "? Answer 2 === 
+      > You must provide a valid value"
+    `);
+
+    events.type('2');
+    expect(getScreen()).toMatchInlineSnapshot(`"? Answer 2 === 2"`);
+
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual('2');
+  });
+
+  it('handle asynchronous validation', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'Answer 2 ===',
+      validate(answer) {
+        return new Promise((resolve) => {
+          if (answer === '2') {
+            resolve(true);
+          } else {
+            resolve('Answer must be 2');
+          }
+        });
+      },
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? Answer 2 ==="`);
+
+    events.type('1');
+    expect(getScreen()).toMatchInlineSnapshot(`"? Answer 2 === 1"`);
+
+    events.keypress('enter');
+    await Promise.resolve();
+    expect(getScreen()).toMatchInlineSnapshot(`
+      "? Answer 2 === 
+      > Answer must be 2"
+    `);
+
+    events.type('2');
+    expect(getScreen()).toMatchInlineSnapshot(`"? Answer 2 === 2"`);
+
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual('2');
+  });
+
+  it('handle default option', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'What is your name',
+      default: 'Mike',
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name (Mike)"`);
+
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual('Mike');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name Mike"`);
+  });
+
+  it('handle overwriting the default option', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'What is your name',
+      default: 'Mike',
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name (Mike)"`);
+
+    events.type('John');
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual('John');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name John"`);
+  });
+
+  it('handle removing the default option', async () => {
+    const { answer, events, getScreen } = await render(input, {
+      message: 'What is your name',
+      default: 'Mike',
+    });
+
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name (Mike)"`);
+
+    events.keypress('backspace');
+    events.keypress('enter');
+    await expect(answer).resolves.toEqual('');
+    expect(getScreen()).toMatchInlineSnapshot(`"? What is your name"`);
+  });
+});