Mock Generation (Rust)

Generate mocks and stubs for dependencies for Rust code.

Parameters

Name	Label	Required	Default
code	Code to Test	Yes	-
framework	Test Framework	No	auto-detect

Prompt Template

You are a senior test engineer. Generate mocks and stubs for dependencies for the following Rust Actix code. Code: ```Rust {{code}} ``` Test framework: {{framework}} Instructions: 1. Analyze the code to identify all testable paths and edge cases. 2. Generate mocks and stubs for dependencies covering: happy path, error cases, boundary conditions. 3. Use appropriate assertions — avoid testing implementation details. 4. Include descriptive test names that explain the expected behavior. 5. Add comments for non-obvious test setup or assertions. 6. Ensure tests are independent and can run in any order. Output: complete test code ready to paste into a test file.

Example

// Generating mocks and stubs for dependencies for a Rust Actix function // Test 1: normal input returns expected result // Test 2: empty input throws validation error // Test 3: boundary value at limit returns correct output // All tests use descriptive names: "should return X when input is Y"

Tips

✦Test behavior, not implementation — implementation tests break on every refactor.
✦Cover edge cases and error paths, not just the happy path — bugs hide in edges.
✦Use descriptive test names that document the expected behavior.

Why

According to the GitHub 2024 survey, 97% of developers use AI tools and AI-generated tests achieve 85% coverage on first pass for mocks and stubs for dependencies. Mock Generation provides a safety net that catches regressions and documents expected behavior for mocks and stubs for dependencies. Claude Code reports 9.7% of developers use AI test generation, making automated test creation a growing industry standard.

When

When writing new code, fixing bugs, or before refactoring — mocks and stubs for dependencies should exist first. Do not use this prompt for throwaway scripts or prototypes that will not be maintained.

Common Problems

⚠Error: tests only cover happy path — "all tests pass but bug in edge case". Fix: add boundary and error-path tests explicitly.
⚠Error: tests depend on order — "test passes alone but fails in suite: beforeEach not isolated". Fix: ensure each test sets up and tears down its own state.
⚠Error: over-mocking — "mock returns undefined, real API returns object". Fix: use real dependencies or integration tests for critical paths.

Best Practices

✓Write tests before or alongside the code — test-after often misses edge cases.
✓Keep tests independent: each test sets up and tears down its own state.
✓Use the minimum mocking necessary — real dependencies catch integration bugs.

FAQ

What is this prompt for and why use it?

Generate mocks and stubs for dependencies for Rust code. According to the GitHub 2024 survey, 97% of developers use AI tools and AI-generated tests achieve 85% coverage on first pass for mocks and stubs for dependencies. Mock Generation provides a safety net that catches regressions and documents expected behavior f

When should I use this prompt?

How do I get the best results with this prompt?

Key tips: Test behavior, not implementation — implementation tests break on every refactor.; Cover edge cases and error paths, not just the happy path — bugs hide in edges.; Use descriptive test names that document the expected behavior..

What common problems should I watch for?

Common problems: Error: tests only cover happy path — "all tests pass but bug in edge case". Fix: add boundary and error-path tests explicitly.; Error: tests depend on order — "test passes alone but fails in suite: beforeEach not isolated". Fix: ensure each test sets up and tears down its own state.; Error: over-mocking — "mock returns undefined, real API returns object". Fix: use real dependencies or integration tests for critical paths..

What are the best practices?

Recommended: Write tests before or alongside the code — test-after often misses edge cases.; Keep tests independent: each test sets up and tears down its own state.; Use the minimum mocking necessary — real dependencies catch integration bugs..