Add a `--force` option to bin/changelog

bin/changelog

@@ -12,6 +12,7 @@ Options = Struct.new(
   :amend,
   :author,
   :dry_run,
+  :force,
   :merge_request,
   :title
 )
@@ -29,6 +30,10 @@ class ChangelogOptionParser
         options.amend = value
       end
 
+      opts.on('-f', '--force', 'Overwrite an existing entry') do |value|
+        options.force = value
+      end
+
       opts.on('-m', '--merge-request [integer]', Integer, 'Merge Request ID') do |value|
         options.merge_request = value
       end
@@ -111,8 +116,9 @@ class ChangelogEntry
 
   def assert_new_file!
     return unless File.exist?(file_path)
+    return if options.force
 
-    fail_with "#{file_path} already exists!"
+    fail_with "#{file_path} already exists! Use `--force` to overwrite."
   end
 
   def assert_title!

doc/development/changelog.md

@@ -46,13 +46,14 @@ author:
 
 The entry filename is based on the name of the current Git branch. If you run
 the command above on a branch called `feature/hey-dz`, it will generate a
-`changelogs/unreleased/feature-hey-dz` file.
+`changelogs/unreleased/feature-hey-dz.yml` file.
 
 ### Arguments
 
 | Argument          | Shorthand | Purpose                                       |
 | ----------------- | --------- | --------------------------------------------- |
 | `--amend`         |           | Amend the previous commit                     |
+| `--force`         | `-f`      | Overwrite an existing entry                   |
 | `--merge-request` | `-m`      | Merge Request ID                              |
 | `--dry-run`       | `-n`      | Don't actually write anything, just print     |
 | `--git-username`  | `-u`      | Use Git user.name configuration as the author |
@@ -79,6 +80,23 @@ merge_request:
 author:
 ```
 
+#### `--force` or `-f`
+
+Use **`--force`** or **`-f`** to overwrite an existing changelog entry if it
+already exists.
+
+```text
+$ bin/changelog 'Hey DZ, I added a feature to GitLab!'
+error changelogs/unreleased/feature-hey-dz.yml already exists! Use `--force` to overwrite.
+
+$ bin/changelog 'Hey DZ, I added a feature to GitLab!' --force
+create changelogs/unreleased/feature-hey-dz.yml
+---
+title: Hey DZ, I added a feature to GitLab!
+merge_request: 1983
+author:
+```
+
 #### `--merge-request` or `-m`
 
 Use the **`--merge-request`** or **`-m`** argument to provide the

spec/bin/changelog_spec.rb

@@ -10,6 +10,18 @@ describe 'bin/changelog' do
       expect(options.amend).to eq true
     end
 
+    it 'parses --force' do
+      options = described_class.parse(%w[foo --force bar])
+
+      expect(options.force).to eq true
+    end
+
+    it 'parses -f' do
+      options = described_class.parse(%w[foo -f bar])
+
+      expect(options.force).to eq true
+    end
+
     it 'parses --merge-request' do
       options = described_class.parse(%w[foo --merge-request 1234 bar])