BEST_PRACTICIES.md

Code deprecation

Whenever you decide to deprecate method/class in our codebase, please do:

1. ideally: remove all the usages of this method/class and method/class itself.
2. at least: write proper explanation why you deprecate it and provide an explicit alternative.

if you make your changes in platform code, consider the impact to all dependent projects.

Cocoapods

Use only specific pod versions in Podfile

Preferred:

pod 'FBAudienceNetwork', '= 4.0'

Not Preferred:

pod 'FBAudienceNetwork', '~> 4.0'

Unit Tests

Given-When-Then

Structure test cases using Given-When-Then pattern.

• The Given section describes pre-conditions to the test.
• The When section contains the code we want to test
• The Then section contains checks we want to perform

Given section may be omitted if there are no specific preconditions.

Comments that separate sections are necessary if test case is too large. In other cases they may be omitted.

Sources:

• https://martinfowler.com/bliki/GivenWhenThen.html
• https://www.objc.io/issues/15-testing/xctest/#given-when-then

Preferred:

func testThat_GivenFilterIsChats_WhenIncomingMessageReceived_ThenUserIsUpdatedWithIncomingMessage() {
    // Given
    let incomingMessage = "incomingMessage"
    self.fakeConnectionsService.filter = .chats
    
    var isUserUpdated = false
    self.fakeConnectionsService.onUpdateUserAtIndex = { (user, index) in
        isUserUpdated = true
        XCTAssertEqual(user.message, incomingMessage)
    }
    
    // When
    self.receive(message: incomingMessage, incoming: true)
    
    // Then
    XCTAssertTrue(isUserUpdated)
}

Tear down

XCTestCase instances are kept alive until all tests passed: https://qualitycoding.org/teardown/ Therefore, state should be cleaned in tearDown() function.

Preferred:

class UserTests: XCTestCase {

    let sut: User!
    
    override func setUp() {
        super.setUp()
        self.sut = User()
    }
    
    override func tearDown() {
        self.sut = nil
        super.tearDown()
    }
    
    func testThat_UserDoSometing() {
        // use sut  
    }
}

Not Preferred:

class UserTests: XCTestCase {

    let sut = User()
    
    func testThat_UserDoSometing() {
        // use sut  
    }
}