find-interfaces

README

find-interfaces

find-interfaces is a small Go CLI that prints interface type names found in Go source files in a single directory.

It is designed for shell usage and works well in pipelines with tools such as gowrap.

What It Does

• Scans .go files in the target directory
• Parses source code using Go's AST
• Extracts declared interface type names
• Ignores subdirectories
• Prints results as a single space-separated line

Requirements

• Go 1.25 or later

Installation

Install the latest version:

go install github.com/adlandh/find-interfaces@latest

Build from source:

go build .

Development

Run all tests:

go test ./...

Match CI test settings:

go test -race -coverprofile=coverage.txt -covermode=atomic ./...

Inspect coverage by function:

go test ./... -coverprofile=coverage.out && go tool cover -func=coverage.out

Match the CI lint flow:

curl -sS https://raw.githubusercontent.com/adlandh/golangci-lint-config/refs/heads/main/.golangci.yml -o .golangci.yml && golangci-lint run

Usage

Search the current directory:

find-interfaces

Search a specific directory:

find-interfaces -path /path/to/package

Show help:

find-interfaces -h

Example

Given this Go source:

package sample

type Reader interface {
	Read([]byte) (int, error)
}

type Writer[T any] interface {
	Write(T) error
}

type handlerFunc func()

Running:

find-interfaces -path ./sample

Produces:

Reader Writer

Behavior

• Only the top-level target directory is scanned
• Only files with a .go extension are considered
• File extension matching is case-insensitive
• Comments and string literals that merely contain interface-like text are ignored
• Files with parse errors may still contribute interface names when the AST is partially recoverable
• Output order follows file traversal order and is not explicitly sorted

Exit Behavior

• On success, the tool prints discovered interface names to standard output
• If no interfaces are found, it prints nothing
• On failure, it exits with a non-zero status and prints an error message

Typical Pipeline Use

for iface in $(find-interfaces -path ./pkg/service); do
  gowrap gen -p ./pkg/service -i "$iface" -t fallback -o "./pkg/service/${iface,,}_wrapper.go"
done

Limitations

• It does not recurse into nested directories
• It does not filter by package name
• It only reports interface names, not file paths or method details

Documentation

Overview

Package main provides a utility to find Go interface definitions in a directory.