affaan-m/ecc

rust-testing

Rust testing patterns including unit tests, integration tests, async testing, property-based testing, mocking, and coverage.

查看源码

先看实际效果

作者示例

Source example: Rust red and green TDD stages

Both complete author blocks are separate successive stages: replace the todo-based function with the green implementation rather than compiling duplicate add definitions together. A crate is required. The source PASS/panic comments describe expected stages, not tests run by this site.

示例输入

```rust
// RED: Write test first, use todo!() as placeholder
pub fn add(a: i32, b: i32) -> i32 { todo!() }

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_add() { assert_eq!(add(2, 3), 5); }
}
// cargo test → panics at 'not yet implemented'
```

```rust
// GREEN: Replace todo!() with minimal implementation
pub fn add(a: i32, b: i32) -> i32 { a + b }
// cargo test → PASS, then REFACTOR while keeping tests green
```
许可

Complete original source block(s), unchanged; enclosing Markdown fences omitted for a single block or retained between grouped blocks. Editorial title and prerequisite summary added. Source code and assertions were not executed.

MIT License

Copyright (c) 2026 Affaan Mustafa

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
作者示例

Source example: property tests and custom strategies

Two complete proptest blocks cover round trips, sort length/order and generated email-like inputs. Requires proptest plus your encode/decode and User implementations. Repeated imports belong to example sections; this is not complete email validation or an executed test suite.

示例输入

```rust
use proptest::prelude::*;

proptest! {
    #[test]
    fn encode_decode_roundtrip(input in ".*") {
        let encoded = encode(&input);
        let decoded = decode(&encoded).unwrap();
        assert_eq!(input, decoded);
    }

    #[test]
    fn sort_preserves_length(mut vec in prop::collection::vec(any::<i32>(), 0..100)) {
        let original_len = vec.len();
        vec.sort();
        assert_eq!(vec.len(), original_len);
    }

    #[test]
    fn sort_produces_ordered_output(mut vec in prop::collection::vec(any::<i32>(), 0..100)) {
        vec.sort();
        for window in vec.windows(2) {
            assert!(window[0] <= window[1]);
        }
    }
}
```

```rust
use proptest::prelude::*;

fn valid_email() -> impl Strategy<Value = String> {
    ("[a-z]{1,10}", "[a-z]{1,5}")
        .prop_map(|(user, domain)| format!("{user}@{domain}.com"))
}

proptest! {
    #[test]
    fn accepts_valid_emails(email in valid_email()) {
        assert!(User::new("Test", &email).is_ok());
    }
}
```
许可

Complete original source block(s), unchanged; enclosing Markdown fences omitted for a single block or retained between grouped blocks. Editorial title and prerequisite summary added. Source code and assertions were not executed.

MIT License

Copyright (c) 2026 Affaan Mustafa

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
作者示例

Source example: mock a repository trait

Complete original mockall trait and found/missing-user tests. Requires mockall plus matching User, StorageError and UserService definitions not supplied by this block. Expected mock calls/assertions are preserved; no independent test pass is claimed.

示例输入

use mockall::{automock, predicate::eq};

#[automock]
trait UserRepository {
    fn find_by_id(&self, id: u64) -> Option<User>;
    fn save(&self, user: &User) -> Result<(), StorageError>;
}

#[test]
fn service_returns_user_when_found() {
    let mut mock = MockUserRepository::new();
    mock.expect_find_by_id()
        .with(eq(42))
        .times(1)
        .returning(|_| Some(User { id: 42, name: "Alice".into() }));

    let service = UserService::new(Box::new(mock));
    let user = service.get_user(42).unwrap();
    assert_eq!(user.name, "Alice");
}

#[test]
fn service_returns_none_when_not_found() {
    let mut mock = MockUserRepository::new();
    mock.expect_find_by_id()
        .returning(|_| None);

    let service = UserService::new(Box::new(mock));
    assert!(service.get_user(99).is_none());
}
许可

Complete original source block(s), unchanged; enclosing Markdown fences omitted for a single block or retained between grouped blocks. Editorial title and prerequisite summary added. Source code and assertions were not executed.

MIT License

Copyright (c) 2026 Affaan Mustafa

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
作者示例

Source example: Criterion benchmark setup

Complete original Cargo benchmark declaration and benches/benchmark.rs. Requires a Rust project and Criterion dependency; the source configuration pins its stated 0.5 range. Fibonacci benchmark code is retained, but no timing, chart or measured improvement is invented.

示例输入

```toml
# Cargo.toml
[dev-dependencies]
criterion = { version = "0.5", features = ["html_reports"] }

[[bench]]
name = "benchmark"
harness = false
```

```rust
// benches/benchmark.rs
use criterion::{black_box, criterion_group, criterion_main, Criterion};

fn fibonacci(n: u64) -> u64 {
    match n {
        0 | 1 => n,
        _ => fibonacci(n - 1) + fibonacci(n - 2),
    }
}

fn bench_fibonacci(c: &mut Criterion) {
    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
}

criterion_group!(benches, bench_fibonacci);
criterion_main!(benches);
```
许可

Complete original source block(s), unchanged; enclosing Markdown fences omitted for a single block or retained between grouped blocks. Editorial title and prerequisite summary added. Source code and assertions were not executed.

MIT License

Copyright (c) 2026 Affaan Mustafa

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

使用方法

  1. 复制安装命令,在自己的智能体环境安装前先检查源码包。
  2. 从原始文档核对所需工具、凭据和支持的宿主。
  3. 说明输入材料与期望交付物,并对照来源检查输出。
npx skills add https://github.com/affaan-m/ecc --skill rust-testing

开始前需了解

  • 安装不包含模型订阅、API 额度或访问文件的权限。
  • 仓库星数和安装量反映活跃情况,不等于独立质量或安全测试。
仓库原始内容

按源仓库内容呈现,保留标题、案例、代码、表格、链接以及原文引用的演示图片。

Rust Testing Patterns

Comprehensive Rust testing patterns for writing reliable, maintainable tests following TDD methodology.

When to Use

  • Writing new Rust functions, methods, or traits
  • Adding test coverage to existing code
  • Creating benchmarks for performance-critical code
  • Implementing property-based tests for input validation
  • Following TDD workflow in Rust projects

How It Works

  1. Identify target code — Find the function, trait, or module to test
  2. Write a test — Use #[test] in a #[cfg(test)] module, rstest for parameterized tests, or proptest for property-based tests
  3. Mock dependencies — Use mockall to isolate the unit under test
  4. Run tests (RED) — Verify the test fails with the expected error
  5. Implement (GREEN) — Write minimal code to pass
  6. Refactor — Improve while keeping tests green
  7. Check coverage — Use cargo-llvm-cov, target 80%+

TDD Workflow for Rust

The RED-GREEN-REFACTOR Cycle

RED     → Write a failing test first
GREEN   → Write minimal code to pass the test
REFACTOR → Improve code while keeping tests green
REPEAT  → Continue with next requirement

Step-by-Step TDD in Rust

rust
// RED: Write test first, use todo!() as placeholder
pub fn add(a: i32, b: i32) -> i32 { todo!() }

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_add() { assert_eq!(add(2, 3), 5); }
}
// cargo test → panics at 'not yet implemented'
rust
// GREEN: Replace todo!() with minimal implementation
pub fn add(a: i32, b: i32) -> i32 { a + b }
// cargo test → PASS, then REFACTOR while keeping tests green

Unit Tests

Module-Level Test Organization

rust
// src/user.rs
pub struct User {
    pub name: String,
    pub email: String,
}

impl User {
    pub fn new(name: impl Into<String>, email: impl Into<String>) -> Result<Self, String> {
        let email = email.into();
        if !email.contains('@') {
            return Err(format!("invalid email: {email}"));
        }
        Ok(Self { name: name.into(), email })
    }

    pub fn display_name(&self) -> &str {
        &self.name
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn creates_user_with_valid_email() {
        let user = User::new("Alice", "alice@example.com").unwrap();
        assert_eq!(user.display_name(), "Alice");
        assert_eq!(user.email, "alice@example.com");
    }

    #[test]
    fn rejects_invalid_email() {
        let result = User::new("Bob", "not-an-email");
        assert!(result.is_err());
        assert!(result.unwrap_err().contains("invalid email"));
    }
}

Assertion Macros

rust
assert_eq!(2 + 2, 4);                                    // Equality
assert_ne!(2 + 2, 5);                                    // Inequality
assert!(vec![1, 2, 3].contains(&2));                     // Boolean
assert_eq!(value, 42, "expected 42 but got {value}");    // Custom message
assert!((0.1_f64 + 0.2 - 0.3).abs() < f64::EPSILON);   // Float comparison

Error and Panic Testing

Testing Result Returns

rust
#[test]
fn parse_returns_error_for_invalid_input() {
    let result = parse_config("}{invalid");
    assert!(result.is_err());

    // Assert specific error variant
    let err = result.unwrap_err();
    assert!(matches!(err, ConfigError::ParseError(_)));
}

#[test]
fn parse_succeeds_for_valid_input() -> Result<(), Box<dyn std::error::Error>> {
    let config = parse_config(r#"{"port": 8080}"#)?;
    assert_eq!(config.port, 8080);
    Ok(()) // Test fails if any ? returns Err
}

Testing Panics

rust
#[test]
#[should_panic]
fn panics_on_empty_input() {
    process(&[]);
}

#[test]
#[should_panic(expected = "index out of bounds")]
fn panics_with_specific_message() {
    let v: Vec<i32> = vec![];
    let _ = v[0];
}

Integration Tests

File Structure

text
my_crate/
├── src/
│   └── lib.rs
├── tests/              # Integration tests
│   ├── api_test.rs     # Each file is a separate test binary
│   ├── db_test.rs
│   └── common/         # Shared test utilities
│       └── mod.rs

Writing Integration Tests

rust
// tests/api_test.rs
use my_crate::{App, Config};

#[test]
fn full_request_lifecycle() {
    let config = Config::test_default();
    let app = App::new(config);

    let response = app.handle_request("/health");
    assert_eq!(response.status, 200);
    assert_eq!(response.body, "OK");
}

Async Tests

With Tokio

rust
#[tokio::test]
async fn fetches_data_successfully() {
    let client = TestClient::new().await;
    let result = client.get("/data").await;
    assert!(result.is_ok());
    assert_eq!(result.unwrap().items.len(), 3);
}

#[tokio::test]
async fn handles_timeout() {
    use std::time::Duration;
    let result = tokio::time::timeout(
        Duration::from_millis(100),
        slow_operation(),
    ).await;

    assert!(result.is_err(), "should have timed out");
}

Test Organization Patterns

Parameterized Tests with rstest

rust
use rstest::{rstest, fixture};

#[rstest]
#[case("hello", 5)]
#[case("", 0)]
#[case("rust", 4)]
fn test_string_length(#[case] input: &str, #[case] expected: usize) {
    assert_eq!(input.len(), expected);
}

// Fixtures
#[fixture]
fn test_db() -> TestDb {
    TestDb::new_in_memory()
}

#[rstest]
fn test_insert(test_db: TestDb) {
    test_db.insert("key", "value");
    assert_eq!(test_db.get("key"), Some("value".into()));
}

Test Helpers

rust
#[cfg(test)]
mod tests {
    use super::*;

    /// Creates a test user with sensible defaults.
    fn make_user(name: &str) -> User {
        User::new(name, &format!("{name}@test.com")).unwrap()
    }

    #[test]
    fn user_display() {
        let user = make_user("alice");
        assert_eq!(user.display_name(), "alice");
    }
}

Property-Based Testing with proptest

Basic Property Tests

rust
use proptest::prelude::*;

proptest! {
    #[test]
    fn encode_decode_roundtrip(input in ".*") {
        let encoded = encode(&input);
        let decoded = decode(&encoded).unwrap();
        assert_eq!(input, decoded);
    }

    #[test]
    fn sort_preserves_length(mut vec in prop::collection::vec(any::<i32>(), 0..100)) {
        let original_len = vec.len();
        vec.sort();
        assert_eq!(vec.len(), original_len);
    }

    #[test]
    fn sort_produces_ordered_output(mut vec in prop::collection::vec(any::<i32>(), 0..100)) {
        vec.sort();
        for window in vec.windows(2) {
            assert!(window[0] <= window[1]);
        }
    }
}

Custom Strategies

rust
use proptest::prelude::*;

fn valid_email() -> impl Strategy<Value = String> {
    ("[a-z]{1,10}", "[a-z]{1,5}")
        .prop_map(|(user, domain)| format!("{user}@{domain}.com"))
}

proptest! {
    #[test]
    fn accepts_valid_emails(email in valid_email()) {
        assert!(User::new("Test", &email).is_ok());
    }
}

Mocking with mockall

Trait-Based Mocking

rust
use mockall::{automock, predicate::eq};

#[automock]
trait UserRepository {
    fn find_by_id(&self, id: u64) -> Option<User>;
    fn save(&self, user: &User) -> Result<(), StorageError>;
}

#[test]
fn service_returns_user_when_found() {
    let mut mock = MockUserRepository::new();
    mock.expect_find_by_id()
        .with(eq(42))
        .times(1)
        .returning(|_| Some(User { id: 42, name: "Alice".into() }));

    let service = UserService::new(Box::new(mock));
    let user = service.get_user(42).unwrap();
    assert_eq!(user.name, "Alice");
}

#[test]
fn service_returns_none_when_not_found() {
    let mut mock = MockUserRepository::new();
    mock.expect_find_by_id()
        .returning(|_| None);

    let service = UserService::new(Box::new(mock));
    assert!(service.get_user(99).is_none());
}

Doc Tests

Executable Documentation

rust
/// Adds two numbers together.
///
/// # Examples
///
/// ```
/// use my_crate::add;
///
/// assert_eq!(add(2, 3), 5);
/// assert_eq!(add(-1, 1), 0);
/// ```
pub fn add(a: i32, b: i32) -> i32 {
    a + b
}

/// Parses a config string.
///
/// # Errors
///
/// Returns `Err` if the input is not valid TOML.
///
/// ```no_run
/// use my_crate::parse_config;
///
/// let config = parse_config(r#"port = 8080"#).unwrap();
/// assert_eq!(config.port, 8080);
/// ```
///
/// ```no_run
/// use my_crate::parse_config;
///
/// assert!(parse_config("}{invalid").is_err());
/// ```
pub fn parse_config(input: &str) -> Result<Config, ParseError> {
    todo!()
}

Benchmarking with Criterion

toml
# Cargo.toml
[dev-dependencies]
criterion = { version = "0.5", features = ["html_reports"] }

[[bench]]
name = "benchmark"
harness = false
rust
// benches/benchmark.rs
use criterion::{black_box, criterion_group, criterion_main, Criterion};

fn fibonacci(n: u64) -> u64 {
    match n {
        0 | 1 => n,
        _ => fibonacci(n - 1) + fibonacci(n - 2),
    }
}

fn bench_fibonacci(c: &mut Criterion) {
    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
}

criterion_group!(benches, bench_fibonacci);
criterion_main!(benches);

Test Coverage

Running Coverage

bash
# Install: cargo install cargo-llvm-cov (or use taiki-e/install-action in CI)
cargo llvm-cov                    # Summary
cargo llvm-cov --html             # HTML report
cargo llvm-cov --lcov > lcov.info # LCOV format for CI
cargo llvm-cov --fail-under-lines 80  # Fail if below threshold

Coverage Targets

Code TypeTarget
Critical business logic100%
Public API90%+
General code80%+
Generated / FFI bindingsExclude

Testing Commands

bash
cargo test                        # Run all tests
cargo test -- --nocapture         # Show println output
cargo test test_name              # Run tests matching pattern
cargo test --lib                  # Unit tests only
cargo test --test api_test        # Integration tests only
cargo test --doc                  # Doc tests only
cargo test --no-fail-fast         # Don't stop on first failure
cargo test -- --ignored           # Run ignored tests

Best Practices

DO:

  • Write tests FIRST (TDD)
  • Use #[cfg(test)] modules for unit tests
  • Test behavior, not implementation
  • Use descriptive test names that explain the scenario
  • Prefer assert_eq! over assert! for better error messages
  • Use ? in tests that return Result for cleaner error output
  • Keep tests independent — no shared mutable state

DON'T:

  • Use #[should_panic] when you can test Result::is_err() instead
  • Mock everything — prefer integration tests when feasible
  • Ignore flaky tests — fix or quarantine them
  • Use sleep() in tests — use channels, barriers, or tokio::time::pause()
  • Skip error path testing

CI Integration

yaml
# GitHub Actions
test:
  runs-on: ubuntu-latest
  steps:
    - uses: actions/checkout@v4
    - uses: dtolnay/rust-toolchain@stable
      with:
        components: clippy, rustfmt

    - name: Check formatting
      run: cargo fmt --check

    - name: Clippy
      run: cargo clippy -- -D warnings

    - name: Run tests
      run: cargo test

    - uses: taiki-e/install-action@cargo-llvm-cov

    - name: Coverage
      run: cargo llvm-cov --fail-under-lines 80

Remember: Tests are documentation. They show how your code is meant to be used. Write them clearly and keep them up to date.

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