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https://github.com/pirishd/instantmock
Create mocks easily in Swift
https://github.com/pirishd/instantmock
mock stub swift swift-protocols swift3 swift4 swift5 unit-testing
Last synced: 3 days ago
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Create mocks easily in Swift
- Host: GitHub
- URL: https://github.com/pirishd/instantmock
- Owner: pirishd
- License: mit
- Created: 2017-05-06T11:34:03.000Z (over 7 years ago)
- Default Branch: dev
- Last Pushed: 2021-05-26T20:04:54.000Z (over 3 years ago)
- Last Synced: 2024-09-24T20:34:28.595Z (3 days ago)
- Topics: mock, stub, swift, swift-protocols, swift3, swift4, swift5, unit-testing
- Language: Swift
- Homepage:
- Size: 465 KB
- Stars: 91
- Watchers: 7
- Forks: 7
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# InstantMock
## Create Mocks Easily in Swift
[](https://travis-ci.org/pirishd/InstantMock/) [](https://codecov.io/gh/pirishd/InstantMock/branch/master) [](https://cocoapods.org/pods/InstantMock) [](https://cocoapods.org/pods/InstantMock)
*InstantMock* aims at creating mocks easily in Swift, and configuring them with expectations or stubbed implementations.
For examples, see `Example.playground`.
Swift versions compatibility:
Swift version | InstantMock version
---|---
5.0 | 2.5.X
4.2 | 2.2.X
4.0 | 2.0/2.1
3.X | 1.1.X
## How to Create a Mock?
*InstantMock* enables to create a single mock that can be used in many tests, for a protocol or a class.
### For a Protocol
The easiest way to create a mock for a protocol is to inherit from the `Mock` class.
```Swift
// MARK: Protocol to be mocked
protocol Foo {
func bar(arg1: String, arg2: Int) -> Bool
}
// MARK: Mock class inherits from `Mock` and adopts the `Foo` protocol
class FooMock: Mock, Foo {
// implement `bar` of the `Foo` protocol
func bar(arg1: String, arg2: Int) -> Bool {
return super.call(arg1, arg2)! // provide values to parent class
}
}
```
### For a Class
To create a mock for a class, the mock must adopt the `MockDelegate` protocol.
```Swift
// MARK: Class to be mocked
class Foo {
func bar(arg1: String, arg2: Int) -> Bool
}
// MARK: Mock class inherits from `Foo` and adopts the `MockDelegate` protocol
class FooMock: Foo, MockDelegate {
// create `Mock` delegate instance
private let mock = Mock()
// conform to the `MockDelegate` protocol, by providing the `Mock` instance
var it: Mock {
return mock
}
// implement `bar` of the `Foo` class
override func bar(arg1: String, arg2: Int) -> Bool {
return mock.call(arg1, arg2)! // provide values to the delegate
}
}
```
### Rules
To work properly, mocks must comply with a few rules regarding return values, due to Swift strong typing.
#### Optional Return Value
The syntax is as follow:
```Swift
func returnsOptional() -> Bool? {
return mock.call()
}
```
Here, `call()` returns `nil` or `Void`.
#### Non-Optional Return Value
For some methods, mocks must return non-optional values. If a return value type adopts the [MockUsable](#mockusable) protocol (which is the case for the most common types like `Bool`, `Int`…), just force unwrapping the result to `call()`, like in the following example:
```Swift
func returnsMockUsable() -> Bool { // `Bool` adopts `MockUsable`
return mock.call()! // force unwrapping
}
```
For other types, make sure to provide a default value, like in the following example:
```Swift
func returnsCustom() -> CustomType {
return mock.call() ?? CustomType() // return a `CustomType` default value
}
```
#### Throwing
For catching errors on throwing methods, simply use `callThrowing()` instead of `call()`.
If a return value type adopts the [MockUsable](#mockusable) protocol (which is the case for the most common types like `Bool`, `Int`…), just force unwrapping the result to `callThrowing()`, like in the following example:
```Swift
func bazMockUsable() throws -> Bool {
return try callThrowing()!
}
```
For other types, make sure to provide a default value, like in the following example:
```Swift
func bazCustom() throws -> CustomType {
return try callThrowing() ?? CustomType() // return a `CustomType` default value
}
```
#### Properties
It is possible to mock properties declared in a protocol, like in the following example:
```Swift
// define protocol with a property `prop` that has a getter and a setter
protocol FooProperty {
var prop: String { get set }
}
// mock of `FooProperty`
class FooPropertyMock: Mock, FooProperty {
var prop: String {
get { return super.call()! }
set { return super.call(newValue) }
}
}
```
## How to Set Expectations?
Expectations aim at verifying that a call is done with some arguments. They are set using a syntax like in the following example:
```Swift
// create mock instance
let mock = FooMock()
// create expectation on `mock`, that is verified when `bar` is called
// with "hello" for `arg1` and any value of the type of `arg2`
mock.expect().call(
mock.bar(arg1: Arg.eq("hello"), arg2: Arg.any())
)
```
### Reject
Rejections are the contrary of expectations. They make sure no call is being done with some arguments. Simply use `reject()` instead of `expect()`.
### Number of calls
In addition, expectations and rejections can be set on the number of calls:
Use the following syntax:
```Swift
// create expectation on `mock`, that is verified when 2 calls are done on `bar`
// with "hello" for `arg1` and any value of the type of `arg2`
mock.expect().call(
mock.bar(arg1: Arg.eq("hello"), arg2: Arg.any()),
count: 2
)
```
### Properties
Setting expectations on properties can be done using the following syntax:
```Swift
// create mock instance
let mock = FooPropertyMock()
// create expectation on `mock`, that is verified when the property `prop` is called
mock.expect().call(mock.prop)
// create expectation on `mock`, that is verified when the property `prop` is set
// with the exact value "hello"
mock.expect().call(
mock.property.set(mock.prop, value: Arg.eq("hello"))
)
```
### Verifications
Verifying expectations and rejections is done this way:
```Swift
// test fails when any of the expectations or rejections set on `mock` is not verified
mock.verify()
```
### Reset Expectations
Expecations can be reset this way:
```Swift
mock.resetExpectations()
```
## How to Stub Calls?
Stubs aim at performing actions when a function is called with some arguments. They are set using a syntax like in the following example:
```Swift
// create mock instance
let mock = FooMock()
// create stubbed implementation of the `bar` method, which returns `true` when called
// with "hello" for `arg1` and any value of the type of `arg2`
mock.stub().call(
mock.bar(arg1: Arg.eq("hello"), arg2: Arg.any())
).andReturn(true)
````
### Return Value
Set the return value with `andReturn(…)` on the stub instance.
### Compute a Return Value
This is done with `andReturn(closure: { _ in return … })` on the stub instance. This enables to return different values on the same stub, depending on some conditions.
### Call Another Function
This is done with `andDo { _ in … } ` on the stub instance.
### Throw an Error
This is done with `andThrow(…)` on the stub instance.
### Chaining
Chaining several actions on the same stub is possible, given they don't confict. For example, it is possible to return a value and call another function, like in `andReturn(true).andDo { _ in print("something") }`.
Rules:
* the last closure registered by `andDo` is called first
* the last error registered by `andThrow` is thrown
* the last return value registered by `andReturn` is returned
* otherwise, the last return value computation method, registered by `andReturn(closure:)`, is called
### Reset Stubs
Stubs can be reset this way:
```Swift
mock.resetStubs()
```
Example:
```Swift
// configure mock to return "string" when calling `basic` whatever provided arguments
mock.stub().call(mock.basic(arg1: Arg.any(), arg2: Arg.any())).andReturn("string")
// reset the previously configured stubs
mock.resetStubs()
// calling `basic` does not return "string"
let ret = mock.basic(arg1: "", arg2: 2)
XCTAssertNotEqual(ret, "string")
```
## Argument Matching
Expectations are verified only if arguments match what is registered. Same goes for calling stubbed implementations.
### Exact Value
Matching an exact value is done with `Arg.eq(…)`.
Values can be matched if they:
- conform to the `AnyObject` protocol, which is the case for all classes implicitly, for example `Arg.eq(NSString("hello"))`
- or conform to the `MockUsable` protocol, for example `Arg.eq(42)`
- or they are types, for example `Arg.eq(String.self)`
- or they are tuples, limited to 5 values, for example `Arg.eq(("a string", 42))`
### Any Value
Matching any value can be done for types that adopt the `MockUsable` protocol, with `Arg.any()`.
### Certain Condition
Matching a value that verifies a certain condition is done with `Arg.verify({ _ in return … })`.
### Closure
Matching a closure is a special case. Use the following syntax: `Arg.closure()`.
*Limitation: closures can be matched as long as they have less than 5 arguments.*
## Argument Capturing
Arguments can also be captured for later use thanks to the `ArgumentCaptor` class.
For example:
```Swift
// create captor for type `String`
let captor = ArgumentCaptor()
// create expectation on `mock`, that is verified when `bar` is called
// with 42 for `arg2`. All values for `arg1` are captured.
mock.expect().call(mock.bar(arg1: captor.capture(), arg2: Arg.eq(42)))
...
// retrieve the last captured value
let value = captor.value
// retrieve all captured values
let values = captor.allValues
```
### Capturing a Closure
Capturing a closure is particularly useful for stubbing the behavior of a method with callbacks, see [this conversation](https://github.com/pirishd/InstantMock/issues/86).
Capturing a closure is a special case. Use the following syntax:
*Limitation: closures can be captured as long as they have less than 5 arguments.*
```Swift
// create captor for type closure `(Int) -> Bool`
let captor = ArgumentClosureCaptor<(Int) -> Bool>()
...
// retrieve the last captured closure, and call it
let ret = captor.value!(42)
```
## MockUsable
`MockUsable` is a protocol that makes types easily usable in mocks.
For a given type, it allows to return non-optional values and to match any values.
Adding `MockUsable` on an existing type is done by creating an extension that adopts the protocol. For example:
```Swift
extension SomeClass: MockUsable {
static var any = SomeClass() // any value
// return any value
public static var anyValue: MockUsable {
return SomeClass.any
}
// returns true if an object is equal to another `MockUsable` object
public func equal(to value: MockUsable?) -> Bool {
guard let value = value as? SomeClass else { return false }
return self == value
}
}
```
Adding `MockUsable` on an existing type that uses inheritance, should always be done on the deepest subclass.
Indeed, adding this extension to both a parent and a subclass would create build conflicts.
### Supported Types
For now, the following types are `MockUsable`:
* Bool
* Int, Int64
* UInt, UInt64
* Float
* Double
* String
* Set
* Array
* Dictionary
* Date
## Changelog
List of changes can be found [here](CHANGELOG.md).
## Requirements
* Xcode 10
* iOS 9
* osX 10.10
## Installation
### Cocoapods
*InstantMock* is available using [CocoaPods](http://cocoapods.org), see `Podfile` example:
```
target 'Example' do
# Tests target
target 'ExampleTests' do
inherit! :search_paths
pod 'InstantMock'
end
end
```
### Swift Package Manager
*InstantMock* is available using the Swift Package Manager, by adding the dependency either with Xcode or by editing the `Package.swift` file:
```
.package(url: "https://github.com/pirishd/InstantMock", from: "2.5.6"),
```
## Inspiration
* Argument Capture: [Mockito](http://mockito.org/)
* Registration API: [SwiftMock](https://github.com/mflint/SwiftMock)
## Author
Patrick Irlande - [email protected]
## License
*InstantMock* is available under the [MIT License](LICENSE).