Tests Developer Skill

Smart router to testing patterns and practices. Writing unit tests, creating mocks, test organization.

When to Use This Skill

This skill activates when working with:

•Writing unit tests
•Creating test mocks
•Testing edge cases
•Test-driven development (TDD)
•Test refactoring and updates
•Swift Testing framework usage
•XCTest framework usage

Quick Reference

Critical Rules

•✅ Use Swift Testing framework (import Testing, @Test, @Suite) for NEW tests
•✅ Keep existing XCTest tests as-is (don't migrate unless necessary)
•✅ Test edge cases: nil values, empty collections, boundary conditions
•✅ Create mock helpers in test file extensions when needed
•✅ Update tests when refactoring - always search and update references
•❌ Never skip tests for data transformation or business logic
•❌ Never use force unwrapping in tests - use proper assertions

Test File Naming

code

ProductionCode:  SetContentViewDataBuilder.swift
Test File:       SetContentViewDataBuilderTests.swift
Location:        AnyTypeTests/[Category]/[TestFile].swift

Swift Testing Framework (Preferred for New Tests)

Basic Structure:

swift

import Testing
import Foundation
@testable import Anytype
import Services

@Suite
struct MyFeatureTests {

    private let sut: MyFeature  // System Under Test

    init() {
        self.sut = MyFeature()
    }

    @Test func testSpecificBehavior() {
        // Arrange
        let input = "test"

        // Act
        let result = sut.process(input)

        // Assert
        #expect(result == "expected")
    }

    @Test func testEdgeCase_EmptyInput_ReturnsNil() {
        let result = sut.process("")
        #expect(result == nil)
    }
}

Suite Options:

swift

@Suite                      // Parallel execution (default)
@Suite(.serialized)        // Sequential execution (for shared state)

Assertions:

swift

#expect(value == expected)           // Equality
#expect(value != unexpected)         // Inequality
#expect(result != nil)               // Not nil
#expect(array.isEmpty)               // Boolean conditions
#expect(throws: SomeError.self) {    // Error throwing
    try throwingFunction()
}

XCTest Framework (Legacy Tests)

Basic Structure:

swift

import XCTest
@testable import Anytype

final class MyFeatureTests: XCTestCase {

    var sut: MyFeature!

    override func setUpWithError() throws {
        sut = MyFeature()
    }

    override func tearDownWithError() throws {
        sut = nil
    }

    func testSpecificBehavior() {
        // Arrange
        let input = "test"

        // Act
        let result = sut.process(input)

        // Assert
        XCTAssertEqual(result, "expected")
    }
}

Common Assertions:

swift

XCTAssertEqual(actual, expected)
XCTAssertNotEqual(actual, unexpected)
XCTAssertNil(value)
XCTAssertNotNil(value)
XCTAssertTrue(condition)
XCTAssertFalse(condition)
XCTAssertThrowsError(try expression)

Test Organization Patterns

1. Edge Case Testing (Critical)

Always test these scenarios:

swift

@Test func testEmptyInput() {
    let result = sut.process([])
    #expect(result.isEmpty)
}

@Test func testNilInput() {
    let result = sut.process(nil)
    #expect(result == nil)
}

@Test func testSingleItem() {
    let result = sut.process([item])
    #expect(result.count == 1)
}

@Test func testBoundaryCondition() {
    let items = (0..<100).map { Item(id: "\($0)") }
    let result = sut.process(items)
    #expect(result.count <= 100)
}

@Test func testTruncation_LimitsToMax() {
    let attachments = (0..<5).map { ObjectDetails.mock(id: "item\($0)") }
    let result = sut.truncate(attachments, limit: 3)
    #expect(result.count == 3)
    #expect(result[0].id == "item0")
    #expect(result[2].id == "item2")
}

2. Mock Helpers (In Test File)

Location: Create as extensions in the same test file

swift

// At bottom of test file
extension ObjectDetails {
    static func mock(id: String) -> ObjectDetails {
        ObjectDetails(id: id, values: [:])
    }
}

extension Participant {
    static func mock(
        id: String,
        globalName: String = "",
        icon: ObjectIcon? = nil
    ) -> Participant {
        Participant(
            id: id,
            localName: "",
            globalName: globalName,
            icon: icon,
            status: .active,
            permission: .reader,
            identity: "",
            identityProfileLink: "",
            spaceId: "",
            type: ""
        )
    }
}

3. Dependency Injection in Tests

Using Factory Pattern:

swift

@Suite(.serialized)  // Required for DI setup
struct MyFeatureTests {

    private let mockService: MyServiceMock

    init() {
        let mockService = MyServiceMock()
        Container.shared.myService.register { mockService }
        self.mockService = mockService
    }

    @Test func testWithMockedDependency() {
        mockService.expectedResult = "test"
        let sut = MyFeature()
        let result = sut.doWork()
        #expect(result == "test")
    }
}

4. Testing Protocols (Make Methods Internal)

Problem: Private methods can't be tested Solution: Use internal access and test via protocol

swift

// Production code - SetContentViewDataBuilder.swift
final class SetContentViewDataBuilder: SetContentViewDataBuilderProtocol {

    // ✅ Internal for testing (not private)
    func buildChatPreview(
        objectId: String,
        spaceView: SpaceView?,
        chatPreviewsDict: [String: ChatMessagePreview]
    ) -> MessagePreviewModel? {
        // Implementation
    }
}

// Test code
@Test func testBuildChatPreview_EmptyDict_ReturnsNil() {
    let result = builder.buildChatPreview(
        objectId: "test",
        spaceView: nil,
        chatPreviewsDict: [:]
    )
    #expect(result == nil)
}

5. Dictionary Conversion Testing

Performance validation:

swift

@Test func testDictionaryConversion_EmptyArray() {
    let items: [Item] = []
    let dict = Dictionary(uniqueKeysWithValues: items.map { ($0.id, $0) })
    #expect(dict.isEmpty)
}

@Test func testDictionaryConversion_MultipleItems() {
    let items = (0..<10).map { Item(id: "item\($0)") }
    let dict = Dictionary(uniqueKeysWithValues: items.map { ($0.id, $0) })

    #expect(dict.count == 10)
    for i in 0..<10 {
        #expect(dict["item\(i)"] != nil)
    }
}

@Test func testDictionaryLookup_O1Performance() {
    let items = (0..<100).map { Item(id: "item\($0)") }
    let dict = Dictionary(uniqueKeysWithValues: items.map { ($0.id, $0) })

    let result = dict["item50"]
    #expect(result != nil)
    #expect(result?.id == "item50")
}

6. Testing with Dates

swift

@Test func testDateFormatting() {
    let date = Date(timeIntervalSince1970: 1700000000)
    let result = formatter.format(date)
    #expect(result.isEmpty == false)
}

@Test func testDateComparison() {
    let now = Date()
    let future = now.addingTimeInterval(3600)
    #expect(future > now)
}

7. Testing Protobuf Models

ChatState example:

swift

@Test func testChatStateCounters() {
    var chatState = ChatState()

    var messagesState = ChatState.UnreadState()
    messagesState.counter = 5
    chatState.messages = messagesState

    var mentionsState = ChatState.UnreadState()
    mentionsState.counter = 2
    chatState.mentions = mentionsState

    #expect(chatState.messages.counter == 5)
    #expect(chatState.mentions.counter == 2)
}

Mock Services Pattern

Preview Mocks (for SwiftUI Previews)

Location: Anytype/Sources/PreviewMocks/

Usage:

swift

import SwiftUI

#Preview {
    MockView {
        // Configure mock state
        SpaceViewsStorageMock.shared.workspaces = [...]
    } content: {
        MyView()
    }
}

Test Mocks (for Unit Tests)

Location: AnyTypeTests/Mocks/ or in test file

Pattern:

swift

@testable import Anytype

final class MyServiceMock: MyServiceProtocol {
    var callCount = 0
    var capturedInput: String?
    var stubbedResult: Result?

    func process(_ input: String) -> Result {
        callCount += 1
        capturedInput = input
        return stubbedResult ?? .default
    }
}

Testing Checklist

When writing tests, ensure:

When Refactoring Production Code

CRITICAL: Always update tests when refactoring:

•Search for test references:

bash

rg "OldClassName" AnyTypeTests/ --type swift
rg "oldPropertyName" AnyTypeTests/ --type swift

•
Update test mocks:
- •Check AnyTypeTests/Mocks/
- •Check Anytype/Sources/PreviewMocks/
- •Update DI registrations in MockView.swift
•
Update mock extensions:
- •Search for .mock( in test files
- •Update parameters if initializer changed
•
Run tests before committing:
- •User will verify in Xcode (faster with caches)
- •Report all test file changes to user

Common Test Patterns in Codebase

Pattern 1: Builder Testing

swift

@Test func testBuilderCreatesCorrectModel() {
    let input = [...setup...]
    let result = builder.build(input)

    #expect(result.property1 == expected1)
    #expect(result.property2 == expected2)
    #expect(result.collection.count == 3)
}

Pattern 2: Storage/Repository Testing

swift

@Suite(.serialized)
struct StorageTests {
    init() {
        // Setup mock dependencies
    }

    @Test func testSaveAndRetrieve() {
        storage.save(item)
        let retrieved = storage.get(item.id)
        #expect(retrieved?.id == item.id)
    }
}

Pattern 3: Parser/Formatter Testing

swift

@Test func testParseValidInput() {
    let result = parser.parse("valid input")
    #expect(result != nil)
}

@Test func testParseInvalidInput_ReturnsNil() {
    let result = parser.parse("")
    #expect(result == nil)
}

Pattern 4: Counter/State Testing

swift

@Test func testCountersPropagation() {
    var model = Model()
    model.state = createState(messages: 5, mentions: 2)

    #expect(model.unreadCounter == 5)
    #expect(model.mentionCounter == 2)
}

Test File Examples

Example 1: SetContentViewDataBuilderTests.swift

Full working example: AnyTypeTests/Services/SetContentViewDataBuilderTests.swift

•Tests builder methods
•Creates mock helpers
•Tests edge cases (nil, empty, truncation)
•Tests counter propagation
•Tests dictionary conversion performance

Example 2: ChatMessageLimitsTests.swift

Full working example: AnyTypeTests/Services/ChatMessageLimitsTests.swift

•Uses @Suite(.serialized) for DI setup
•Mocks date provider via Factory DI
•Tests rate limiting logic
•Tests time-based conditions

tests-developer

Tests Developer Skill

When to Use This Skill

Quick Reference

Critical Rules

Test File Naming

Swift Testing Framework (Preferred for New Tests)

XCTest Framework (Legacy Tests)

Test Organization Patterns

1. Edge Case Testing (Critical)

2. Mock Helpers (In Test File)

3. Dependency Injection in Tests

4. Testing Protocols (Make Methods Internal)

5. Dictionary Conversion Testing

6. Testing with Dates

7. Testing Protobuf Models

Mock Services Pattern

Preview Mocks (for SwiftUI Previews)

Test Mocks (for Unit Tests)

Testing Checklist

When Refactoring Production Code

Common Test Patterns in Codebase

Pattern 1: Builder Testing

Pattern 2: Storage/Repository Testing

Pattern 3: Parser/Formatter Testing

Pattern 4: Counter/State Testing

Test File Examples

Example 1: SetContentViewDataBuilderTests.swift

Example 2: ChatMessageLimitsTests.swift

Related Documentation