gorefactor

A Go tool that finds duplicated string literals in Go source files and suggests refactoring opportunities.

Project Structure

.
├── cmd/
│   └── gorefactor/       # Main application entry point
│       └── main.go
├── pkg/
│   └── duplicates/       # Core logic for finding duplicated literals
│       ├── duplicates.go
│       └── duplicates_test.go
├── Makefile              # Build automation
└── go.mod

Usage

Build the tool:

make build

Or using go directly:

go build -o bin/gorefactor ./cmd/gorefactor

Run it on a Go file:

./bin/gorefactor [flags] <path-to-go-file>

Flags

• --format - Output format: text (default) or json
• --min-count - Minimum number of occurrences to report (default: 2)

Examples

Text output (default):

./bin/gorefactor cmd/gorefactor/main.go
./bin/gorefactor pkg/duplicates/duplicates.go

JSON output (for AI agents and tooling):

./bin/gorefactor --format json cmd/gorefactor/main.go

Filter by minimum occurrences:

./bin/gorefactor --min-count 3 cmd/gorefactor/main.go

Makefile Targets

• make build - Build the gorefactor binary (default)
• make clean - Remove the bin/ directory
• make test - Run tests
• make vet - Run go vet
• make install - Install to GOPATH/bin

Testing

Run the test suite:

make test

Or using go directly:

go test -v ./...

The test suite includes:

• Finding duplicates in test files
• Handling files with no duplicates
• Error handling for invalid files
• Error handling for invalid Go code
• Multiple duplicate detection
• Minimum count filtering
• JSON output round-trip testing

How it works

The tool:

1. Parses the provided Go file into an AST using Go's standard library (pkg/duplicates)
2. Walks the AST to collect all string literals and their line numbers
3. Identifies literals that appear more than the minimum count (default: 2)
4. Generates suggestions for extracting duplicates to constants
5. Outputs the duplicated literals with their locations and suggestions (cmd/gorefactor)

Example Output

Text Format

Duplicate string literals found:

String: "Hello, World!"
  Found 3 times at lines: [7 8 15]
  Suggestion: String "Hello, World!" appears 3 times. Consider extracting to a package-level constant.

String: "example"
  Found 2 times at lines: [6 11]
  Suggestion: String "example" appears 2 times. Consider extracting to a package-level constant.

JSON Format

{
  "file_path": "example.go",
  "duplicates": [
    {
      "value": "\"Hello, World!\"",
      "lines": [7, 8, 15],
      "suggestion": "String \"Hello, World!\" appears 3 times. Consider extracting to a package-level constant."
    },
    {
      "value": "\"example\"",
      "lines": [6, 11],
      "suggestion": "String \"example\" appears 2 times. Consider extracting to a package-level constant."
    }
  ]
}

Contributing

See CONTRIBUTING.md for guidelines on contributing to this project.