Package Exports

betray

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (betray) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

Betray

Minimal test spies, stubs and mocks module.

Installation

npm install betray

Spies, Mocks, Stubs, ZOMBIES!

Creating a spy

var betray = require('betray');

var math = {
  add: function(x, y) {
    return x + y;
  }
};

var betrayedAdd = betray(math, 'add');

var sum = math.add(1, 2);

// Original function was invoked and spies invocation counter incremented
expect(sum).to.equal(3);
expect(betrayedAdd.invoked).to.equal(1);

Stubs

Betray does not offer a stub API or the like 😞. Minimal! Better! Extensible! 👯

var math = {
  add: function(x, y) {
    return x + y;
  }
};

var betrayedAdd = betray(math, 'add', [{ match  : function() { return true; }, handle : function() { return 1; }}]);

// Will not invoke the original add function but will return 1 for every call. 
var betrayedResult = math.add();
expect(betrayedResult).to.equal(1);

// Invocation counter is incremented as well
expect(betrayedThrowError.invoked).to.equal(1);

simpler

var math = {
  add: function(x, y) {
    return x + y;
  }
};

var betrayedAdd = betray(math, 'add', function() { return 1; }); // Returns 1 for all calls

// Will not invoke the original add function but will return 1 for every call. 
var betrayedResult = math.add();
expect(betrayedResult).to.equal(1);

// Invocation counter is incremented as well
expect(betrayedThrowError.invoked).to.equal(1);

even simpler

var math = {
  add: function(x, y) {
    return x + y;
  }
};

var betrayedAdd = betray(math, 'add', 1); // Returns 1

// Will not invoke the original add function but will return 1 for every call. 
var betrayedResult = math.add();
expect(betrayedResult).to.equal(1);

// Invocation counter is incremented as well
expect(betrayedThrowError.invoked).to.equal(1);

Mocks

As mocks are "pre-programmed with expectations which form a specification of the calls they are expected to receive" and we betray in a minimal way we'll use chai expect syntax to create our own mock!

var math = {
  add: function(x, y) {
    return x + y;
  }
};

betray(math, 'add', [{
  match  : function() { return this.add.invoked == 1 },
  handle : function(y) {
    expect(y).to.equal(2);
    return 1;
  }
},{
  match  : function() { return this.add.invoked == 2 },
  handle : function(y) {
    expect(y).to.equal(3);
    return 2;
  }
}]);

// Will not invoke the original add function but will return 1 for every call.
math.add(2);
math.add(3);

simpler

Betray implements some convenience functions to match specific calls

onFirstCall(fn)
onSecondCall(fn)
onThirdCall(fn)
onCall(num, fn)

var math = {
  add: function(x, y) {
    return x + y;
  }
};

betray(math, 'add')
  .onFirstCall(function(y) {
    expect(y).to.equal(2);
    return 1;
  })
  .onSecondCall(function(y) {
    expect(y).to.equal(3);
    return 2;
  });

// Will not invoke the original add function but will return 1 for every call.
math.add(2);
math.add(3);