betray's Introduction

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 :disappoineted:. 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);

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;
  }
};

var betrayedAdd = betray(math, 'add', [{ 
  match  : function() { this.invoked == 0 }, 
  handle : function(y) {
   expect(y).to.equal(2);
   return 1; 
  }
},{ 
  match  : function() { this.invoked == 1 },  
  handle : function(y) {
   expect(y).to.equal(1);
   return 2; 
  }
}

]);

// Will not invoke the original add function but will return 1 for every call. 
math.add(2);
math.add(3); // Will throw because we expected second invocation to have 1 as y argument

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