Fixmie documentation

Welcome to the official Fixmie documentation.

Table of Contents

• Introduction
• Fixers
  • go
• Configuration
  • go
  • ignore

Introduction

Fixmie analyzes and automatically fixes your source code by providing smart and useful suggestions. Fixmie is more powerful than your ordinary linter, it not only provides useful tips, it also rewrites your source code and suggest the changes. It's up to you whether to accept these changes or to decline.

Follow the instructions after authorizing to Github on fixmie.com. Once the Fixmie Github application is installed to the specified repositories, Fixmie listens for pull requests events and checks each changed file in that particular pull request.

Each file is checked by multiple fixers concurrently, independently from each other. This means there might be one or multiple fixes for a single line.

Fixers

Fixmie contains multiple fixers for various kind of checks. The current set of supported fixers are:

go

The go fixer supports the following modes for the Go programming language:

• comments:
  • Rewrites existing comments if first word doesn't match exported identifier
  • Rewrites existing comments first word is Foo to Foo ...
• errors:
  • Replaces errors.New(fmt.Sprintf(...)) with fmt.Errorf(...)
  • Replaces t.Error(fmt.Sprintf(...)) with t.Errorf(...)
  • Removes following ending characters from error strings:
    • punctuation .
    • colon :
    • newline \n
    • exclamation marks !
• errwrap:
  • Wrap and fix Go errors with the new %w verb directive. This fixer uses the errwrap analyzer: https://github.com/fatih/errwrap
• returns:
  • Moves the position of an error return if isn't the last parameter of a function declaration. I.e: func foo() (error, int) is replaced with func foo() (int, error). The mode also updates all returns in the function declaration.
• formats:
  • Formats and fixes the lines that are not formatted according to gofmt rules.
• params:
  • Simplifies function parameters and results to omit the type if two consecutive types are the same (i.e: func foo(a int, b int) -> func foo(a, b int)
• builtins:
  • Checks identifier's that shadows a predefined identifier (builtin), such as new, len, delete, etc... Replaces the identifiers and the local usages, i,e: len := 5 -> length := 5.
• times:
  • Improves time package usages:
    • simplifies time.Now().Sub(t) -> time.Since(t)
    • simplifies t.Sub(time.Now()) -> time.Until(t)

The go fixer ignores certain types of files and folders:

• vendor/ folders
• files ending with .pb.go or .gen.go
• files and folders starting with underscore (i.e: _foo.go or _test-fixtures/)
• generated files containing the rule ^// Code generated .* DO NOT EDIT\.$, for more information checkout the definition: https://golang.org/s/generatedcode

Configuration

IMPORTANT: the configuration file format is not final yet and can be changed during the Beta stage. Please check this page occasionally to see the breaking changes.

You can configure certain aspects of Fixmie by adding the .fixmie.yml file to your repository. An example configuration might look like:

go:
  comments:
    disabled: true

ignore:
 - "test_data/"
 - "*.js.go"

go

The go field can be used to configure certain aspects of the go fixer. Each field under the go field is named according to the mode (see the Fixers section). The following example shows all current options:

go:
  comments:
    disabled: true
  errors:
    disabled: true
  errwrap:
    disabled: true
  returns:
    disabled: true
  formats:
    disabled: true
  params:
    disabled: true
  builtins:
    disabled: true
  times:
    disabled: true

Currently, you can disable each individual mode. For example, defining the following configuration will disable the comments mode for each consecutive PR's:

go:
  comments:
    disabled: true

In the future, we're planning to add even deeper customizations for each mode.

ignore

The ignore field can be used to ignore files or folders. It's an array of strings, where each item should be specified according to the gitignore rules: https://git-scm.com/docs/gitignore

This is a global setting and applies to all fixers.

Example usage:

# ignores any file under test_data and files ending with .js.go
ignore:
 - "test_data/"
 - "*.js.go"

The ignore field is combined with the default ignore list of each fixer. As an example, adding the following won't have any effect because vendor/ is already ignored:

# this won't have any effect on the `go` fixer, because 
# these files/folders are already ignored by the `go` fixer.
ignore:
 - "_*.go"
 - "vendor/"