https://github.com/kakkoyun/demo-error-lint
A demo program to check/try out error linters
https://github.com/kakkoyun/demo-error-lint
Last synced: about 2 months ago
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A demo program to check/try out error linters
- Host: GitHub
- URL: https://github.com/kakkoyun/demo-error-lint
- Owner: kakkoyun
- License: mit
- Created: 2025-03-03T14:28:47.000Z (2 months ago)
- Default Branch: main
- Last Pushed: 2025-03-03T14:36:16.000Z (2 months ago)
- Last Synced: 2025-03-03T15:38:02.084Z (2 months ago)
- Language: Go
- Homepage:
- Size: 5.86 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Go Error Linting Demo
A demo program to check/try out error linters. This repository demonstrates various error handling patterns in Go—both problematic ones and their correct alternatives—to test the capabilities of error linters like [go-errorlint](https://github.com/polyfloyd/go-errorlint).
## Goals
- Demonstrate common error handling anti-patterns in Go
- Show how to properly handle errors using the errors package introduced in Go 1.13
- Provide a test bed for error linting tools
- Illustrate how automatic fixes work with error linters
## Error Patterns Demonstrated
This demo includes examples of:
1. **Direct error comparisons** (`err == ErrSomething`) instead of `errors.Is()`
2. **Error type assertions** (`err.(*CustomError)`) instead of `errors.As()`
3. **Type switches** on errors instead of using `errors.As()`
4. **Missing error wrapping** with `fmt.Errorf()` using `%v` instead of `%w`
5. **String matching** (`strings.Contains(err.Error(), "text")`) instead of proper error handling
6. **Special cases** like handling of documented errors like `io.EOF` and `sql.ErrNoRows`
## Usage
### Building and Running
```bash
# Build the demo program
make build
# Run the demo program
make run
```
### Using the Error Linter
```bash
# Run the linter to check for issues
make lint
# Auto-fix issues where possible
make lint-fix
```
## What the Linter Will Find
The linter will detect issues like:
```go
// ISSUE: Direct comparison instead of errors.Is
if err == ErrInvalidInput {
// ...
}
// ISSUE: Type assertion instead of errors.As
notFoundErr, ok := err.(*NotFoundError)
// ISSUE: Using %v instead of %w in fmt.Errorf
return fmt.Errorf("failed to process data: %v", err)
```
## Correct Patterns
The demo also shows correct error handling patterns:
```go
// Correct: Using errors.Is
if errors.Is(err, ErrInvalidInput) {
// ...
}
// Correct: Using errors.As
var notFound *NotFoundError
if errors.As(err, ¬Found) {
// ...
}
// Correct: Using %w to wrap errors
return fmt.Errorf("operation failed: %w", err)
```
## License
This project is open source and available under the [MIT License](LICENSE).