Change Validation Skill

When to Use

Use this skill when:

•Code changes have been applied
•You want to ensure they compile/run correctly
•You need quick validation before committing
•Testing after code generation

Validation Steps

1. Format Check

bash

cargo fmt --check

Ensures code follows Rust formatting standards.

2. Lint Check (Clippy)

bash

cargo clippy -- -D warnings

Catches common mistakes and anti-patterns.

3. Compile

bash

cargo build

Verifies the code compiles without errors.

4. Run Tests

bash

cargo test

Ensures existing functionality still works.

Quick Validation

For a fast check without tests:

bash

cargo fmt --check && cargo clippy -- -D warnings && cargo build

Full Validation (Recommended)

bash

cargo fmt --check && cargo clippy -- -D warnings && cargo build && cargo test

Understanding Output

Format Issues:

code

error: `should be` ... (run `cargo fmt` to fix)

→ Run cargo fmt to auto-fix

Clippy Warnings:

code

warning: field is never read: `field`

→ Remove unused code or address the warning

Compile Errors:

code

error[E0425]: cannot find value `x` in this scope

→ Check variable names and scope

Test Failures:

code

thread 'test_name' panicked at 'assertion failed'

→ Review the test and the code change

After Validation

If all checks pass ✓:

•Changes are ready
•Safe to commit/push
•Proceed with workflow

If issues found ✗:

•Review the error messages
•Ask Claude to fix specific issues
•Run validation again

Example Session

code

You: "Generate a function to parse JSON"
Claude: [Writes parse function]
[Stop hook runs diffy review]
You: Accept all changes ✓
[Validation runs]
```bash
cargo test  # All tests pass

→ Ready to commit!

code


## Troubleshooting

**Tests are timing out?**
- Run single test: `cargo test test_name -- --nocapture`
- Check for infinite loops

**Build fails after changes?**
- Check compiler error message
- Review what Claude changed
- Ask Claude to fix compilation error

**Tests fail but code looks right?**
- Run tests with output: `cargo test -- --nocapture`
- Review test expectations
- Update tests if behavior changed intentionally

See `/diffy:help` for review commands.