Swift Test Suite Builder

Swift Testing Standards

by HoangNguyen0403 · MIT license · ★ 569 on GitHub

Write XCTest cases, async tests, and organized test suites in Swift. Use when writing XCTest cases, async tests, or organizing test suites in Swift.

---
name: swift-testing
description: Write XCTest cases, async tests, and organized test suites in Swift. Use when writing XCTest cases, async tests, or organizing test suites in Swift.
metadata:
  triggers:
    files:
    - '**/*Tests.swift'
    keywords:
    - XCTestCase
    - XCTestExpectation
    - XCTAssert
---
# Swift Testing Standards

## **Priority: P0 (CRITICAL)**

## Core Rule Anchors

Overview

See implementation examples for XCTest setup/teardown, async tests, and UI test patterns.

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Swift Testing Standards

Priority: P0 (CRITICAL)

Core Rule Anchors

[MOB-TEST-01] Tripartite Naming: Test functions must follow test_method_scenario_expectedBehavior or testMethod_scenario_expectedBehavior.
[MOB-TEST-02] State Invariant Rule: Assert state transitions and invariants; ban trivial state mirror tests.
[MOB-TEST-03] Entity Invariant & Codable Rule: Test calculations, validations, domain invariants, and non-trivial Codable serialization/parsing or error mapping; ban testing trivial getters or echo tests.
[MOB-TEST-04] Contract Testing Rule: Repositories and data sources must be tested for contract compliance and error mapping; ban 1:1 pass-through mock echoing.
[MOB-TEST-05] Bug-First Regression Lock: Every PR fixing a bug ticket or with title fix(...) must introduce a test reproducing the defect prior to the fix.

Write XCTest Cases

Standard Naming: Test functions must prefixed by 'test' ([MOB-TEST-01], e.g., func test_userLogin_whenValid_isSuccessful()).
Setup/Teardown: Use setUpWithError() and tearDownWithError() for environment management.
Assertions: Use specific assertions: XCTAssertEqual, XCTAssertNil, XCTAssertTrue, etc.

See implementation examples for XCTest setup/teardown, async tests, and UI test patterns.

Test Async Code

Async/Await: Mark test methods as async throws and use try await directly inside them.
Expectations: Use XCTestExpectation for callback-based async logic. Call expectation then fulfill() when done; then wait(for: [exp], timeout: 2.0) to block.
Timeout: Always set reasonable timeouts for expectations to avoid hanging CI.

Organize Test Suites

Unit Tests: Use protocols for dependencies and inject them via constructor (e.g., init(service: ServiceProtocol)). Focus on logic isolation using mocks/stubs.
UI Tests: Test user flows using XCUIApplication and accessibility identifiers.
Coverage: Coverage is diagnostic and project-configured; verify risk-weighted critical paths rather than padding code for an arbitrary percentage.

Anti-Patterns

[MOB-TEST-01..05] Violations: Ban vague names, trivial state mirrors, echo tests, 1:1 mock echoing, and unverified bug fixes.
No Thread.sleep: Use expectations or await.
No force unwrap in tests: Use XCTUnwrap() for better failure messages.
No assertion-free tests: A test that only runs code without asserting contract invariants is not a test.

References

XCTest Patterns & Async Tests

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

Inject them via constructor
Use protocols
prefixed by 'test'

1	---
2	name: swift-testing
3	description: Write XCTest cases, async tests, and organized test suites in Swift. Use when writing XCTest cases, async tests, or organizing test suites in Swift.
4	metadata:
5	triggers:
6	files:
7	- '*/Tests.swift'
8	keywords:
9	- XCTestCase
10	- XCTestExpectation
11	- XCTAssert
12	---
13	# Swift Testing Standards
14
15	## Priority: P0 (CRITICAL)
16
17	## Core Rule Anchors
18
19	- `[MOB-TEST-01]` Tripartite Naming: Test functions must follow `test_method_scenario_expectedBehavior` or `testMethod_scenario_expectedBehavior`.
20	- `[MOB-TEST-02]` State Invariant Rule: Assert state transitions and invariants; ban trivial state mirror tests.
21	- `[MOB-TEST-03]` Entity Invariant & Codable Rule: Test calculations, validations, domain invariants, and non-trivial `Codable` serialization/parsing or error mapping; ban testing trivial getters or echo tests.
22	- `[MOB-TEST-04]` Contract Testing Rule: Repositories and data sources must be tested for contract compliance and error mapping; ban 1:1 pass-through mock echoing.
23	- `[MOB-TEST-05]` Bug-First Regression Lock: Every PR fixing a bug ticket or with title `fix(...)` must introduce a test reproducing the defect prior to the fix.
24
25	## Write XCTest Cases
26
27	- Standard Naming: Test functions must prefixed by 'test' (`[MOB-TEST-01]`, e.g., `func test_userLogin_whenValid_isSuccessful()`).
28	- Setup/Teardown: Use `setUpWithError()` and `tearDownWithError()` for environment management.
29	- Assertions: Use specific assertions: `XCTAssertEqual`, `XCTAssertNil`, `XCTAssertTrue`, etc.
30
31	See [implementation examples](references/implementation.md) for XCTest setup/teardown, async tests, and UI test patterns.
32
33	## Test Async Code
34
35	- Async/Await: Mark test methods as `async throws` and use `try await` directly inside them.
36	- Expectations: Use `XCTestExpectation` for callback-based async logic. Call `expectation` then `fulfill()` when done; then `wait(for: [exp], timeout: 2.0)` to block.
37	- Timeout: Always set reasonable timeouts for expectations to avoid hanging CI.
38
39	## Organize Test Suites
40
41	- Unit Tests: Use protocols for dependencies and inject them via constructor (e.g., `init(service: ServiceProtocol)`). Focus on logic isolation using mocks/stubs.
42	- UI Tests: Test user flows using `XCUIApplication` and accessibility identifiers.
43	- Coverage: Coverage is diagnostic and project-configured; verify risk-weighted critical paths rather than padding code for an arbitrary percentage.
44
45	## Anti-Patterns
46
47	- `[MOB-TEST-01..05]` Violations: Ban vague names, trivial state mirrors, echo tests, 1:1 mock echoing, and unverified bug fixes.
48	- No Thread.sleep: Use expectations or await.
49	- No force unwrap in tests: Use `XCTUnwrap()` for better failure messages.
50	- No assertion-free tests: A test that only runs code without asserting contract invariants is not a test.
51
52	## References
53
54	- [XCTest Patterns & Async Tests](references/implementation.md)
55
56	## Canonical response anchors
57
58	When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:
59	- Inject them via constructor
60	- Use protocols
61	- prefixed by 'test'
62