ztrace/test/index.js

strace for node

'use strict';

const ZTrace = require('..');
const assert = require('assert');
const path = require('path');

describe('ZTrace', function() {
  it('Can hook into an object and watch its calls', function() {
    const obj = {
      method(arg) {
        return arg + 42;
      }
    };

    const infos = [];

    const ztrace = new ZTrace.ZTrace();
    ztrace.setupHooks()
      .on('enter', info => infos.push(['enter', info]))
      .on('leave', info => infos.push(['leave', info]));

    const hObj = ztrace.hookValue('obj', obj);

    const ret = hObj.method(20);
    assert.strictEqual(ret, 62);
    assert.strictEqual(infos.length, 2);
    assert.strictEqual(infos[0][0], 'enter');
    assert.strictEqual(infos[1][0], 'leave');
    assert.strictEqual(infos[0][1], infos[1][1]);
    assert.strictEqual(infos[0][1].newTarget, null);
    assert.strictEqual(infos[0][1].name, 'obj.method');
    assert.strictEqual(infos[0][1].localName, 'obj.method');
    assert.strictEqual(infos[0][1].thisArg, obj);
    assert.strictEqual(infos[0][1].depth, 0);
    assert.strictEqual(infos[0][1].callID, 0);
    assert.strictEqual(infos[0][1].ret, 62);
    assert.strictEqual(infos[0][1].exception, undefined);
  });

  it('Can hook get stack trace information if desired', function() {
    const obj = {
      method(arg) {
        return arg + 42;
      }
    };

    const infos = [];

    const ztrace = new ZTrace.ZTrace({ gatherCallSites: true });
    ztrace.setupHooks()
      .on('enter', info => infos.push(['enter', info]))
      .on('leave', info => infos.push(['leave', info]));

    const hObj = ztrace.hookValue('obj', obj);

    const ret = hObj.method(20);
    assert.strictEqual(ret, 62);
    assert.strictEqual(infos.length, 2);
    assert.strictEqual(infos[0][0], 'enter');
    assert.strictEqual(infos[1][0], 'leave');
    assert.strictEqual(infos[0][1], infos[1][1]);
    assert.strictEqual(typeof infos[0][1].stack[0].column, 'number');
    assert.strictEqual(typeof infos[0][1].stack[0].line, 'number');
    assert.strictEqual(infos[0][1].stack[0].file, __filename);
  });

  it('Hooks into an return values of functions', function() {
    const obj = {
      method(arg) {
        return () => {
          return arg + 42;
        };
      }
    };

    const infos = [];

    const ztrace = new ZTrace.ZTrace();
    ztrace.setupHooks()
      .on('enter', info => infos.push(['enter', info]))
      .on('leave', info => infos.push(['leave', info]));

    const hObj = ztrace.hookValue('obj', obj);

    const ret = hObj.method(20)();
    assert.strictEqual(ret, 62);
    assert.strictEqual(infos.length, 4);
    assert.strictEqual(infos[0][0], 'enter');
    assert.strictEqual(infos[1][0], 'leave');
    assert.strictEqual(infos[2][0], 'enter');
    assert.strictEqual(infos[3][0], 'leave');
    assert.strictEqual(infos[2][1], infos[3][1]);
    assert.strictEqual(infos[2][1].newTarget, null);
    assert.strictEqual(infos[2][1].name, 'obj.method()');
    assert.strictEqual(infos[2][1].localName, 'obj.method()');
    assert.strictEqual(infos[2][1].thisArg, undefined);
    assert.strictEqual(infos[2][1].depth, 0);
    assert.strictEqual(infos[2][1].callID, 1);
    assert.strictEqual(infos[2][1].ret, 62);
    assert.strictEqual(infos[2][1].exception, undefined);
  });

  it('Can display new.target', function() {
    class A {
      constructor() {
        this.a = 42;
      }
    }

    const infos = [];

    const ztrace = new ZTrace.ZTrace();
    ztrace.setupHooks()
      .on('enter', info => infos.push(['enter', info]))
      .on('leave', info => infos.push(['leave', info]));

    class B extends ztrace.hookValue('A', A) {}

    new B();

    assert.strictEqual(infos.length, 2);
    assert.strictEqual(infos[0][0], 'enter');
    assert.strictEqual(infos[1][0], 'leave');
    assert.strictEqual(infos[0][1], infos[1][1]);
    assert.strictEqual(infos[0][1].newTarget, B);
    assert.strictEqual(infos[0][1].name, 'A');
    assert.strictEqual(infos[0][1].localName, 'new A');
    assert.strictEqual(infos[0][1].thisArg, null);
    assert.strictEqual(infos[0][1].depth, 0);
    assert.strictEqual(infos[0][1].callID, 0);
    assert.strictEqual(infos[0][1].exception, undefined);
  });

  it('Hooks into an return values of functions', function() {
    const obj = {
      method(arg) {
        return () => {
          return arg + 42;
        };
      }
    };

    const infos = [];

    const ztrace = new ZTrace.ZTrace();
    ztrace.setupHooks()
      .on('enter', info => infos.push(['enter', info]))
      .on('leave', info => infos.push(['leave', info]));

    const hObj = ztrace.hookValue('obj', obj);

    const ret = hObj.method(20)();
    assert.strictEqual(ret, 62);
    assert.strictEqual(infos.length, 4);
    assert.strictEqual(infos[0][0], 'enter');
    assert.strictEqual(infos[1][0], 'leave');
    assert.strictEqual(infos[2][0], 'enter');
    assert.strictEqual(infos[3][0], 'leave');
    assert.strictEqual(infos[2][1], infos[3][1]);
    assert.strictEqual(infos[2][1].newTarget, null);
    assert.strictEqual(infos[2][1].name, 'obj.method()');
    assert.strictEqual(infos[2][1].localName, 'obj.method()');
    assert.strictEqual(infos[2][1].thisArg, undefined);
    assert.strictEqual(infos[2][1].depth, 0);
    assert.strictEqual(infos[2][1].callID, 1);
    assert.strictEqual(infos[2][1].ret, 62);
    assert.strictEqual(infos[2][1].exception, undefined);
  });
});