https://github.com/dczajkowski/snapshy

📸 A package for running snapshot tests in Elixir
https://github.com/dczajkowski/snapshy

elixir elixir-lang elixir-language package snapshot-testing testing

Last synced: 12 days ago
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📸 A package for running snapshot tests in Elixir

• Host: GitHub
• URL: https://github.com/dczajkowski/snapshy
• Owner: DCzajkowski
• Created: 2019-05-04T02:38:20.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2023-09-15T03:28:38.000Z (about 1 year ago)
• Last Synced: 2024-09-14T07:27:57.008Z (about 2 months ago)
• Topics: elixir, elixir-lang, elixir-language, package, snapshot-testing, testing
• Language: Elixir
• Homepage: https://hexdocs.pm/snapshy
• Size: 48.8 KB
• Stars: 18
• Watchers: 2
• Forks: 3
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

        
# Snapshy

Snapshy is an Elixir package for running snapshot tests in ExUnit.

## Alternatives

When I was creating Snapshy I didn't know of any package that would support snapshot testing in Elixir. Since, I have found @assert-value's [assert_value_elixir](https://github.com/assert-value/assert_value_elixir), which is more feature-rich and more polished. If you need something very light-weight, Snapshy might be a good choice. However, if you want interactivity and more features, give [assert_value_elixir](https://hex.pm/packages/assert_value) a try :)

## Installation

Add `snapshy` to your list of dependencies in `mix.exs` and run `mix deps.get`:

```elixir

def deps do

  [

    # ...

    {:snapshy, "~> 0.2"}

  ]

end

```

## Overview

The way this works:

1. Add Snapshy to the test

```diff

 defmodule TokenizerTest do

+  use Snapshy

   use ExUnit.Case

   # ...

 end

```

2. Replace `test` with `test_snapshot`

```diff

-  test "correctly tokenizes booleans" do

+  test_snapshot "correctly tokenizes booleans" do

     # ...

   end

```

3. Replace an assertion with simple function call

```diff

-    assert(

-      tokens("true false") == [

-        boolean: "true",

-        boolean: "false"

-      ]

-    )

+    tokens("true false")

```

The first time a snapshot will be created in `test/__snapshots__/path/to/test_file/function_name.stub`. The second time, an assertion will be made against the snapshot. If you make changes and you want to update snapshots, run `SNAPSHY_OVERRIDE=true mix test` instead of `mix test`. Verify in git every change is correct.

Alternatively, you can use a macro call instead of the `test_snapshot` macro like so:

```elixir

test "correctly tokenizes booleans" do

  match_snapshot tokens("true false")

end

```

**Careful!** There can only be one `match_snapshot` call per test macro call.