docs/features.md

# Features

This document describes the features supported by this extension.

## Table of Contents

* [IntelliSense](#intellisense)
  * [Code completion](#code-completion)
  * [Signature help](#signature-help)
  * [Quick info on hover](#quick-info-on-hover)
* [Code Navigation](#code-navigation)
  * [Go to definition](#go-to-definition)
  * [Go to symbol](#go-to-symbol)
  * [Find references](#find-references)
  * [Find interface implementations](#find-interface-implementations)
  * [Document outline](#document-outline)
  * [Toggle between code and tests](#toggle-between-code-and-tests)
* [Code Editing](#code-editing)
  * [Snippets](#snippets)
  * [Format and organize imports](#format-and-organize-imports)
    * [Add import](#add-import)
  * [Rename symbol](#rename-symbol)
  * [Refactor](#refactor)
* [Code Generation](#code-generation)
  * [Add or remove struct tags](#add-or-remove-struct-tags)
  * [Generate interface implementation](#generate-interface-implementation)
  * [Generate unit tests](#generate-unit-tests)
  * [Fill struct literals](#fill-struct-literals)
* [Diagnostics](#diagnostics)
  * [Build errors](#build-errors)
  * [Vet errors](#vet-errors)
  * [Lint errors](#lint-errors)
* [Run and test in the editor](#run-and-test-in-the-editor)
  * [Run your code](#run-your-code)
  * [Test and benchmark](#test-and-benchmark)
  * [Code coverage](#code-coverage)
* [Debug your code](#debugging)
* [Other](#other)
  * [Go Playground](#go-playground)

## [IntelliSense](https://code.visualstudio.com/docs/editor/intellisense)

### Code completion

Completion results appear for symbols as you type. You can trigger this manually with the Ctrl+Space shortcut.

Autocompletion is also supported for packages you have not yet imported into your program.

<div style="text-align: center;"><img src="images/completion-signature-help.gif" alt="Code completion and signature help"  style="width: 75%"> </div>

### Signature help

Information about the signature of a function pops up as you type in its parameters.
### Quick info on hover

Documentation appears when you hover over a symbol.

## [Code Navigation](https://code.visualstudio.com/docs/editor/editingevolved)

### Go to definition

Jump to or peek a symbol's declaration.

<div style="text-align: center;"><img src="images/gotodefinition.gif" alt="Go to definition using the context menu" style="width: 75%"> </div>

### Find references

Find or go to the references of a symbol.

This feature is not available if you are using Go modules **without** [`gopls`](gopls.md), the Go language server.

<div style="text-align: center;"><img src="images/findallreferences.gif" alt="Find references using the context menu" style="width: 75%"> </div>

### Find interface implementations

Find the concrete types that implement a given interface.

This feature is not available if you are using Go modules **without** [`gopls`](gopls.md), the Go language server.

<div style="text-align: center;"><img src="images/implementations.gif" alt="Go to implementations for Server that implements http.Handler and then finds all implementations of http.Handler in the workspace" style="width: 75%"> </div>

### [Go to symbol](https://code.visualstudio.com/docs/editor/editingevolved#_go-to-symbol)

Search for symbols in your file or workspace by opening the Command Palette (Ctrl+Shift+P) and typing `@` for symbols in the current file or `#` for symbols in the entire workspace.

<div style="text-align: center;"><img src="images/workspace-symbols.gif" alt="Use Workspace Symbols to locate Hello in the workspace" style="width: 75%"> </div>

### Call hierarchy

Show all calls from or to a function.

<div style="text-align: center;"><img src="images/callhierarchy.gif" alt="Show call hierarchy and investigate callers of a function" style="width: 75%"> </div>

### Document outline

See all the symbols in the current file in the VS Code's [Outline view](https://code.visualstudio.com/docs/getstarted/userinterface#_outline-view).

<div style="text-align: center;"><img src="images/outline.png" alt="Outline of a Go file" style="width: 75%"> </div>

### Toggle between code and tests

Quickly toggle between a file and its corresponding test file by using the [`Go: Toggle Test File`](commands.md#go-toggle-test-file) command.

<div style="text-align: center;"><img src="images/toggletestfile.gif" alt="Toggle between reverse.go and reverse_test.go" style="width: 75%"> </div>

## Code Editing

### [Snippets](https://code.visualstudio.com/docs/editor/userdefinedsnippets)

Predefined snippets for quick coding. These snippets will appear as completion suggestions when you type. Users can also define their own custom snippets (see [Snippets in Visual Studio Code](https://code.visualstudio.com/docs/editor/userdefinedsnippets#_create-your-own-snippets)).

<div style="text-align: center;"><img src="images/snippets-tys.gif" alt="Use the struct type snippet" style="width: 75%"> </div>

### Format and organize imports

Format code and organize imports, either manually or on save.

#### Add import

Manually add a new import to your file through the [`Go: Add Import`](commands.md#go-add-import) command. Available packages are offered from your `GOPATH` and module cache.

<div style="text-align: center;"><img src="images/addimport.gif" alt="Add byte import to Go file" style="width: 75%"> </div>


### [Rename symbol](https://code.visualstudio.com/docs/editor/refactoring#_rename-symbol)

Rename all occurrences of a symbol in your workspace.

**Note**: For undo after rename to work on Windows, you need to have `diff` tool on your `PATH`.

This feature is not available if you are using Go modules **without** [`gopls`](gopls.md), the Go language server.

<div style="text-align: center;"><img src="images/rename.gif" alt="Rename an exported variable in Go workspace" style="width: 75%"> </div>


### Refactor

Select the area for refactoring (e.g. variable, function body, etc). Click on the Code Action light bulb icon
that appears in the selected area, or select "Refactoring..." or "Rename Symbol" from the VS Code Context menu.
For known issues with this feature see [golang/go#37170](https://github.com/golang/go/issues/37170).

<div style="text-align: center;"><img src="images/extract-variable.gif" alt="Extract to variable followed by a rename" style="width: 75%"> </div>

## Code Generation

### Add or remove struct tags

Use the [`Go: Add Tags to Struct Fields`](commands.md#go-add-tags-to-struct-fields) command to automatically generate or remove [tags](https://pkg.go.dev/reflect?tab=doc#StructTag) for your struct. This feature is provided by the [`gomodifytags`](tools.md#gomodifytags) tool.

<div style="text-align: center;"><img src="images/addtagstostructfields.gif" alt="Add tags to struct fields" style="width: 75%"> </div>

### Generate interface implementation

Use the [`Go: Generate Interface Stubs`](commands.md#go-generate-interface-stubs) command to automatically generate method stubs for a given interface. This feature is provided by the [`impl`](tools.md#impl) tool.

<div style="text-align: center;"><img src="images/generateinterfaceimplementation.gif" alt="Generate functions to implement an interface" style="width: 75%"> </div>

### Generate unit tests

Easily generate unit tests for your project by running one of the [`Go: Generate Unit Tests for ...`](commands.md#go-generate-unit-tests-for-file) commands. This can be done at a function, file, or package level. This feature is provided by the [`gotests`](tools.md#gotests) tool.

<div style="text-align: center;"><img src="images/generateunittestsforfunction.gif" alt="Generate unit tests for a function" style="width: 75%"> </div>

### Fill struct literals

Use the [`Go: Fill struct`](commands.md#fill-struct) command to automatically fill a struct literal with its default values.

<div style="text-align: center;"><img src="images/fillstructliterals.gif" alt="Fill struct literals" style="width: 75%"> </div>

## Diagnostics

Learn more about [diagnostic errors](tools.md#diagnostics).

### Build errors

Build errors can be shown as you type or on save. Configure this behavior through the [`"go.buildOnSave"`](settings.md#go.buildOnSave) setting.

By default, code is compiled using the `go` command (`go build`), but build errors as you type are provided by the [`gotype-live`](tools.md#diagnostics) tool.

### Vet errors

Vet errors can be shown on save. The vet-on-save behavior can also be configured through the [`"go.vetOnSave"`](settings.md#go.vetOnSave) setting.

The vet tool used is the one provided by the `go` command: [`go vet`](https://golang.org/cmd/vet/).

### Lint errors

Much like vet errors, lint errors can also be shown on save. This behavior is configurable through the [`"go.lintOnSave"`](settings.md#go.lintOnSave) setting.

The default lint tool is [`staticcheck`]. However, custom lint tools can be easily used instead by configuring the [`"go.lintTool"`](settings.md#go.lintTool) setting. [`golint`], [`golangci-lint`], and [`revive`] are also supported.

For a complete overview of linter options, see the [documentation for diagnostic tools](tools.md#diagnostics).

## Run and test in the editor

### Run your code

To run your code without debugging, use the keyboard shortcut `Ctrl+F5` or run the command `Debug: Start without Debugging`. To debug, see [Debugging](#debugging) below.

This command requires you to have a [launch configuration](debugging.md#launch-configuration) in a `launch.json` file. To open or create your `launch.json`, run the `Debug: Open launch.json` command. Use the default `Go: Launch file` configuration.

Behind the scenes, the `Debug: Start without Debugging` command calls `go run`. `go run` usually requires the path to the file to run, so your `launch.json` should contain `"program": "${file}"`.

### Test and benchmark

[Test UI](https://code.visualstudio.com/api/extension-guides/testing) and [Code lenses](https://code.visualstudio.com/blogs/2017/02/12/code-lens-roundup) allow users to easily run tests and benchmarks for a given function, file, package, or workspace. Alternatively, the same functionality is available through a set of commands: [`Go: Test Function At Cursor`](commands.md#go-test-function-at-cursor), [`Go: Test File`](commands.md#go-test-file), [`Go: Test Package`](commands.md#go-test-package), and [`Go: Test All Packages in Workspace`](commands.md#go-test-all-packages-in-workspace).

<div style="text-align: center;"><img src="images/testexplorer.gif" alt="Testing UI" style="width: 75%"> </div>

### Code Coverage

Show code coverage in the editor, either after running a test or on-demand. This can be done via the commands: [`Go: Apply Cover Profile`](commands.md#go-apply-cover-profile) and [`Go: Toggle Test Coverage in Current Package`](commands.md#go-toggle-test-coverage-in-current-package).

## [Debugging](debugging.md)

This extension offers debugging of Go programs. See the [debugging documentation](debugging.md) for more information.

## Other

### Go Playground

Export your current file to the [Go Playground](https://play.golang.org) via the [`Go: Run On Go Playground`](settings.md#go-run-on-go-playground) command. This is useful for quickly creating a piece of sample code.

[`gopls`]: gopls.md
[`staticcheck`]: https://staticcheck.io/
[`golint`]: https://pkg.go.dev/golang.org/x/lint/golint?tab=overview
[`golangci-lint`]: https://golangci-lint.run/
[`revive`]: https://github.com/mgechev/revive