node/test/parallel/test-repl-preview.js

'use strict';

const common = require('../common');
const assert = require('assert');
const events = require('events');
const { REPLServer } = require('repl');
const { Stream } = require('stream');
const { inspect } = require('util');

common.skipIfInspectorDisabled();

// Ignore terminal settings. This is so the test can be run intact if TERM=dumb.
process.env.TERM = '';
const PROMPT = 'repl > ';

class REPLStream extends Stream {
  readable = true;
  writable = true;

  constructor() {
    super();
    this.lines = [''];
  }
  run(data) {
    for (const entry of data) {
      this.emit('data', entry);
    }
    this.emit('data', '\n');
  }
  write(chunk) {
    const chunkLines = chunk.toString('utf8').split('\n');
    this.lines[this.lines.length - 1] += chunkLines[0];
    if (chunkLines.length > 1) {
      this.lines.push(...chunkLines.slice(1));
    }
    this.emit('line', this.lines[this.lines.length - 1]);
    return true;
  }
  async wait() {
    this.lines = [''];
    for await (const [line] of events.on(this, 'line')) {
      if (line.includes(PROMPT)) {
        return this.lines;
      }
    }
  }
  pause() {}
  resume() {}
}

function runAndWait(cmds, repl) {
  const promise = repl.inputStream.wait();
  for (const cmd of cmds) {
    repl.inputStream.run(cmd);
  }
  return promise;
}

async function tests(options) {
  const repl = new REPLServer({
    prompt: PROMPT,
    stream: new REPLStream(),
    ignoreUndefined: true,
    useColors: true,
    ...options
  });

  repl.inputStream.run([
    'function foo(x) { return x; }',
    'function koo() { console.log("abc"); }',
    'a = undefined;',
  ]);

  const testCases = [{
    input: 'foo',
    noPreview: '[Function: foo]',
    preview: [
      'foo',
      '\x1B[90m[Function: foo]\x1B[39m\x1B[11G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[36m[Function: foo]\x1B[39m',
    ]
  }, {
    input: 'koo',
    noPreview: '[Function: koo]',
    preview: [
      'k\x1B[90moo\x1B[39m\x1B[9G',
      '\x1B[90m[Function: koo]\x1B[39m\x1B[9G\x1B[1A\x1B[1B\x1B[2K\x1B[1A' +
        '\x1B[0Ko\x1B[90mo\x1B[39m\x1B[10G',
      '\x1B[90m[Function: koo]\x1B[39m\x1B[10G\x1B[1A\x1B[1B\x1B[2K\x1B[1A' +
        '\x1B[0Ko',
      '\x1B[90m[Function: koo]\x1B[39m\x1B[11G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[36m[Function: koo]\x1B[39m',
    ]
  }, {
    input: 'a',
    noPreview: 'repl > ', // No "undefined" output.
    preview: ['a\r'] // No "undefined" preview.
  }, {
    input: " { b: 1 }['b'] === 1",
    noPreview: '\x1B[33mtrue\x1B[39m',
    preview: [
      " { b: 1 }['b']",
      '\x1B[90m1\x1B[39m\x1B[22G\x1B[1A\x1B[1B\x1B[2K\x1B[1A ',
      '\x1B[90m1\x1B[39m\x1B[23G\x1B[1A\x1B[1B\x1B[2K\x1B[1A=== 1',
      '\x1B[90mtrue\x1B[39m\x1B[28G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33mtrue\x1B[39m',
    ]
  }, {
    input: "{ b: 1 }['b'] === 1;",
    noPreview: '\x1B[33mfalse\x1B[39m',
    preview: [
      "{ b: 1 }['b']",
      '\x1B[90m1\x1B[39m\x1B[21G\x1B[1A\x1B[1B\x1B[2K\x1B[1A ',
      '\x1B[90m1\x1B[39m\x1B[22G\x1B[1A\x1B[1B\x1B[2K\x1B[1A=== 1',
      '\x1B[90mtrue\x1B[39m\x1B[27G\x1B[1A\x1B[1B\x1B[2K\x1B[1A;',
      '\x1B[90mfalse\x1B[39m\x1B[28G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33mfalse\x1B[39m',
    ]
  }, {
    input: '{ a: true }',
    noPreview: '{ a: \x1B[33mtrue\x1B[39m }',
    preview: [
      '{ a: tru\x1B[90me\x1B[39m\x1B[16G\x1B[0Ke }\r',
      '{ a: \x1B[33mtrue\x1B[39m }',
    ]
  }, {
    input: '{ a: true };',
    noPreview: '\x1B[33mtrue\x1B[39m',
    preview: [
      '{ a: tru\x1B[90me\x1B[39m\x1B[16G\x1B[0Ke };',
      '\x1B[90mtrue\x1B[39m\x1B[20G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33mtrue\x1B[39m',
    ]
  }, {
    input: ' \t { a: true};',
    noPreview: '\x1B[33mtrue\x1B[39m',
    preview: [
      '  { a: tru\x1B[90me\x1B[39m\x1B[18G\x1B[0Ke}',
      '\x1B[90m{ a: true }\x1B[39m\x1B[20G\x1B[1A\x1B[1B\x1B[2K\x1B[1A;',
      '\x1B[90mtrue\x1B[39m\x1B[21G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33mtrue\x1B[39m',
    ]
  }, {
    input: '1n + 2n',
    noPreview: '\x1B[33m3n\x1B[39m',
    preview: [
      '1n + 2',
      '\x1B[90mType[39m\x1B[14G\x1B[1A\x1B[1B\x1B[2K\x1B[1An',
      '\x1B[90m3n\x1B[39m\x1B[15G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33m3n\x1B[39m',
    ]
  }, {
    input: '{};1',
    noPreview: '\x1B[33m1\x1B[39m',
    preview: [
      '{};1',
      '\x1B[90m1\x1B[39m\x1B[12G\x1B[1A\x1B[1B\x1B[2K\x1B[1A\r',
      '\x1B[33m1\x1B[39m',
    ]
  }];

  const hasPreview = repl.terminal &&
    (options.preview !== undefined ? !!options.preview : true);

  for (const { input, noPreview, preview } of testCases) {
    console.log(`Testing ${input}`);

    const toBeRun = input.split('\n');
    let lines = await runAndWait(toBeRun, repl);

    if (hasPreview) {
      // Remove error messages. That allows the code to run in different
      // engines.
      // eslint-disable-next-line no-control-regex
      lines = lines.map((line) => line.replace(/Error: .+?\x1B/, ''));
      assert.strictEqual(lines.pop(), '\x1B[1G\x1B[0Jrepl > \x1B[8G');
      assert.deepStrictEqual(lines, preview);
    } else {
      assert.ok(lines[0].includes(noPreview), lines.map(inspect));
      if (preview.length !== 1 || preview[0] !== `${input}\r`)
        assert.strictEqual(lines.length, 2);
    }
  }
}

tests({ terminal: false }); // No preview
tests({ terminal: true }); // Preview
tests({ terminal: false, preview: false }); // No preview
tests({ terminal: false, preview: true }); // No preview
tests({ terminal: true, preview: true }); // Preview