MagicalMock is a convenience class for simplify creation of mock objects and functions for testing purposes. This package is a port of the python unittest.mock, with additional features for JavaScript.
npm install magical-mockMagicalMock is a convenience class for simplify creation of mock objects and functions for testing purposes. This package is a port of the python unittest.mock, with additional features for JavaScript.
``sh`
npm i --save-dev magical-mock
js
//given this hypothetical game function
function gameWorld(world) {
if(world.player.meta.logged_in == true) {
return world.greet(player);
}else{
return world.disconnect(player)
}
}it("Should let the logged in player see the greeeting", function() {
//if you wanted to test this function you might do something like the following
var world = {
player: {
meta: {
logged_in: true
},
name: "Foo"
},
greet: function(player) {
return "hello " + player.name;
},
disconnect: function(player) {
throw Error("logged in player should not disconnect");
}
}
expect(gameWorld(world)).to.equal("hello Foo");
});
//Now with mock we can do better with less code
it("Should let the logged in player see the greeeting", function() {
let world = new Mock();
world.player.meta.logged_in = true;
gameWorld(world);
world.greet.assert_called_once_with(world.player);
world.disconnect.assert_not_called();
`
Magic
A mock object can generate properties when asked for. This makes targeting and replacing deeply nested properties within objects very quick.
js
let mock = new Mock();
mock.deeply.nested.prop = true
mock.always.returns.a.new.mock = true
mock.a.b.c.d.e.f.g.h = 10
mock.lets.place.a.func = function() { return false};
`Documentation
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* Properties
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A boolean value which is set to true if the mock object is used as a function and called.
__Examples__
js
let mock = new Mock();
mock.called //false
mock();
mock.called //true
`---------------------------------------
$3
An integer count of the number of times the mock object has been called as a function.
__Examples__
js
let mock = new Mock();
mock();
mock();
mock.call_count; //2
`---------------------------------------
$3
A list of the arguments last used when calling the mock object as a function.
__Examples__
js
let mock = new Mock();
mock(1,2);
mock.call_args; //[1,2]
`---------------------------------------
$3
A list of argument lists of the arguments used when calling the mock object as a function.
__Examples__
js
let mock = new Mock();
mock(1,2);
mock(3,4);
mock.call_args_list; //[[1,2], [3,4]]
`---------------------------------------
$3
Calling a mock object as a function by default returns another mock object. However, by assigning return\_value to a value the mock will return that value instead.
__Examples__
js
let mock = new Mock();
mock.return_value = 4;
mock() //4
`---------------------------------------
$3
Side\_effect allows the function to return successive values, throw errors, or substitute your own function for calling the mock as a function.
__Examples__
js
let mock = new Mock();
mock.side_effect = [1,2,Error("Problems occurred")];
mock() //1
mock() //2
mock() //throw Error("Problems occurred") let mock2 = new Mock();
mock2.side_effect = function(input) {
if(input == 1) {
return "foo";
}else if(input == 2) {
return "bar";
}else{
return "baz";
}
}
mock2(1) //foo
mock2(2) //bar
mock2(3) //baz
let mock3 = new Mock();
mock3.side_effect = RangeError("Mock has gone too far");
mock3() //throws RangeError
`---------------------------------------
$3
Spec allows the mock to be assigned a prototype
__Examples__
js
class Foo {};
let mock = new Mock();
mock.spec = Foo;
mock instanceof Foo //true
`---------------------------------------
$3
If you would like to use a mock as a contructor function you can specify what it will create.
__Examples__
js
let mock = Mock();
mock.constructs = {x: 1, y: 2};
let result = new mock(); //{x: 1, y: 2}
`---------------------------------------
$3
If you would like to use a mock in a context as an iterator you can specify a value, or series of values, or an error to throw. If a generator function is provided instead then it will use that.
__Examples__
js
let mock = new Mock();
mock.yields = [1,2, Error("explosion")]
for(let item of mock) {
console.log(item);
}
//1
//2
//throws Error("foo") let mock2 = new Mock();
mock2.yields = function () { yield [1,2] }
for(let item of mock2) {
console.log(item);
}
//1
//2
`---------------------------------------
Methods
$3
Asserts that the arguments were the last arguments used when calling the mock object as a function
__Arguments__
*
- Variadic arguments matching the replaced function__Examples__
`js
let mock = new Mock();
mock(3,4);
mock(1,2);
mock.assert_called_with(1,2) //passes
mock.assert_called_with(3,4) //throws Error
`---------------------------------------
$3
Asserts that the mock was called once and only once with the specified arguments.
__Arguments__
*
- Variadic arguments matching the replaced function__Examples__
`js
let mock = new Mock();
mock(1,2);
mock.assert_called_once_with(1,2); //passes
mock.assert_called_once_with(3,4); //throws Error because args do not match
mock(3,4)
mock.assert_called_once_with(3,4); //throws Error because mock was called more than once
`---------------------------------------
$3
Asserts that the mock was called with specified arguments at least once.
__Arguments__
*
- Variadic arguments matching the replaced function__Examples__
`js
let mock = new Mock();
mock(1,2);
mock(3,4);
mock.assert_any_call(1,2); //passes
mock.assert_any_call(3,4); //passes
mock.assert_any_call(4,5); //throws Error
`---------------------------------------
$3
Asserts that the mock was called with the specified list of argument lists, with the option to ensure the order of calls matched the list or to disregard order.
__Arguments__
*
- list of argument lists
* any_order - boolean deciding if calls order should be respected__Examples__
`js
let mock = new Mock();
mock(1,2);
mock(3,4);
mock(4,5);
mock.assert_has_calls([[3,4],[4,5]]) //passes
mock.assert_has_calls([[1,2],[4,5]]) //throws Error
mock.assert_has_calls([[1,2],[4,5]], true) //passes
`---------------------------------------
$3
Asserts that the mock was not called as a function.
__Examples__
js
let mock = new Mock();
mock.assert_not_called(); //passes
mock(1,2);
mock.assert_not_called(); //throws Error
``