Ignore commit messages if they match regular expression

README.md

@@ -36,7 +36,8 @@ Every commit between current HEAD and specified commit will be checked.
 ## Configuration
 
 The behavior of Poper can be controlled via the `.poper.yml` configuration
-file. It must be placed in your project directory. A sample file, `.poper.sample.yml`, is included for easy setup.
+file. It must be placed in your project directory. A sample file, `.poper.sample.yml`, is included
+for easy setup.
 
 The file has the following format:
 
@@ -74,7 +75,62 @@ enforce_capitalized:
   enabled: true
 ```
 
-All properties that can be specified via `.poper.yml`, can also be specified
-via environment variables. Their names will be the upcased path to the property.
-For example: `POPER_ENFORCE_CAPITALIZED_ENABLED` or `POPER_DISALLOW_GENERIC_WORDS`. (In the case of the latter, since environment variables don't support arrays, use a comma-separated list of words and poper will parse them appropriately.) Environment variables
-will always take precedence over values in configuration file.
+All properties that can be specified via `.poper.yml`, can also be specified via environment
+variables. Their names will be the upcased path to the property. For example:
+`POPER_ENFORCE_CAPITALIZED_ENABLED` or `POPER_DISALLOW_GENERIC_WORDS`. (In the case of the latter,
+since environment variables don't support arrays, use a comma-separated list of words and poper will
+parse them appropriately.) Environment variables will always take precedence over values in
+configuration file.
+
+## Ignoring commits
+
+```
+Merge pull request #12345 from myLongUsername/plus-a-long-feature-branch-name
+```
+The above commit message would fail the `character_limit` and `summary_character_limit` checks
+unless the number of allowed characters were set to a high number. Since the commit was
+automatically generated, it may not be desirable to check it.
+
+You can ignore commit messages matching a certain pattern by adding the following settings either to
+`character_limit` or `summary_character_limit`:
+
+```yaml
+# Adding to .poper.yml
+
+character_limit:
+  ignore_if_message_matches: '^Merge pull request'
+
+summary_character_limit:
+  ignore_if_summary_matches: '^Merge pull request'
+```
+
+```
+# Or to ENV vars
+
+POPER_CHARACTER_LIMIT_IGNORE_IF_MESSAGE_MATCHES='^Merge pull request'
+POPER_SUMMARY_CHARACTER_LIMIT_IGNORE_IF_SUMMARY_MATCHES='^Merge pull request'
+```
+
+Note there is a naming difference: `ignore_if_message_matches` versus `ignore_if_summary_matches`.
+
+With a few exceptions, the string you pass to this setting will be used to create a regular
+expression directly.
+```ruby
+Regexp.new('^Merge pull request')
+```
+
+The ignore settings are `nil` by default. If a setting is `nil` or `false`, its rule ignores no
+commit messages. If a setting is `true`, it ignores ALL commit messages (not recommended).
+
+If you want to escape a character in a pattern string, you will need to escape it twice.
+For example:
+```ruby
+string = "Look: ^ a caret"
+escaped_once = "Look: \^ a caret"
+escaped_twice = "Look: \\^ a caret"
+
+Regexp.new(escaped_once).match?(string)  # => false
+Regexp.new(escaped_twice).match?(string) # => true
+```
+This is necessary because Ruby encloses all strings in double quotes when it loads the configuration
+YAML.

lib/poper/config_file.rb

@@ -6,11 +6,13 @@ class ConfigFile
       },
       'character_limit' => {
         'enabled' => true,
-        'number' => 72
+        'number' => 72,
+        'ignore_if_message_matches' => nil
       },
       'summary_character_limit' => {
         'enabled' => true,
-        'number' => 50
+        'number' => 50,
+        'ignore_if_summary_matches' => nil
       },
       'disallow_generic' => {
         'enabled' => true,

lib/poper/regexp.rb

@@ -0,0 +1,40 @@
+# A regular expression that may be initialized with any value that responds to `to_s`.
+#
+# @param [Object] init_value
+#   The value from which to create a regular expression. Must respond to `to_s`.
+#   If `init_value` is `true`, the regular expression will match against all strings.
+#   If `init_value` is `false` or `nil`, the regular expression will match against no strings.
+#
+# @param [Object] options
+#   From 'https://ruby-doc.org/core-2.3.0/Regexp.html#method-c-new':
+#   'If options is an Fixnum, it should be one or more of the constants Regexp::EXTENDED,
+#   Regexp::IGNORECASE, and Regexp::MULTILINE, or-ed together.
+#   'Otherwise, if options is not nil or false, the regexp will be case insensitive.'
+module Poper
+  class Regexp < ::Regexp
+    ANY_STRING_MATCHER = ''
+    NO_STRING_MATCHER = '.^'
+    INIT_VALUES_MATCHING_ALL_STRINGS = [true].freeze
+    INIT_VALUES_MATCHING_NO_STRINGS = [nil, false].freeze
+
+    def initialize(init_value, options = nil)
+      @init_value = init_value
+      super(modified_init_value, options)
+    end
+
+    private
+
+    attr_reader :init_value
+
+    def modified_init_value
+      case init_value
+      when *INIT_VALUES_MATCHING_ALL_STRINGS
+        ANY_STRING_MATCHER
+      when *INIT_VALUES_MATCHING_NO_STRINGS
+        NO_STRING_MATCHER
+      else
+        init_value.to_s
+      end
+    end
+  end
+end

lib/poper/rule/character_limit.rb

@@ -1,7 +1,13 @@
+require 'poper/rule/ignore/matching_pattern'
+
 module Poper
   module Rule
     class CharacterLimit < Rule
+      include Ignore::MatchingPattern
+
       def check(message)
+        return if should_ignore?(message, ignore_pattern: ignore_message_pattern)
+
         error_message if message.lines.any? do |line|
           line.chomp.length > character_limit
         end
@@ -20,6 +26,10 @@ def character_limit
       def error_message
         "Every line of git commit message should be #{character_limit} chars or less"
       end
+
+      def ignore_message_pattern
+        @config.character_limit_ignore_if_message_matches
+      end
     end
   end
 end

lib/poper/rule/ignore/matching_pattern.rb

@@ -0,0 +1,15 @@
+require 'poper/regexp'
+
+# Provides an interface to determine whether a rule should be ignored.
+# Matches a string against a pattern to make this determination.
+module Poper
+  module Rule
+    module Ignore
+      module MatchingPattern
+        def should_ignore?(string, ignore_pattern: nil)
+          Regexp.new(ignore_pattern).match?(string)
+        end
+      end
+    end
+  end
+end

lib/poper/rule/summary_character_limit.rb

@@ -1,8 +1,15 @@
+require 'poper/rule/ignore/matching_pattern'
+
 module Poper
   module Rule
     class SummaryCharacterLimit < Rule
+      include Ignore::MatchingPattern
+
       def check(message)
-        error_message if message.lines.first.chomp.length > character_limit
+        summary = message.lines.first.chomp
+        return if should_ignore?(summary, ignore_pattern: ignore_summary_pattern)
+
+        error_message if summary.length > character_limit
       end
 
       def enabled?
@@ -18,6 +25,10 @@ def character_limit
       def error_message
         "Git commit message summary (first line) should be #{character_limit} chars or less"
       end
+
+      def ignore_summary_pattern
+        @config.summary_character_limit_ignore_if_summary_matches
+      end
     end
   end
 end

poper.gemspec

@@ -20,7 +20,7 @@ Gem::Specification.new do |s|
   s.require_paths = ['lib']
   s.executables << 'poper'
 
-  s.add_runtime_dependency('rugged', '~> 0.23', '>= 0.23.0')
+  s.add_runtime_dependency('rugged', '~> 0.23.0')
   s.add_runtime_dependency('thor', '~> 0.20.0')
   s.add_development_dependency('bundler', '>= 1.10')
   s.add_development_dependency('codeclimate-test-reporter', '~> 1.0')

spec/poper/config_file_spec.rb

@@ -21,7 +21,8 @@ module Poper
           should include(
             'character_limit' => {
               'enabled' => true,
-              'number' => 72
+              'number' => 72,
+              'ignore_if_message_matches' => nil
             }
           )
         end
@@ -30,7 +31,8 @@ module Poper
           should include(
             'summary_character_limit' => {
               'enabled' => true,
-              'number' => 50
+              'number' => 50,
+              'ignore_if_summary_matches' => nil
             }
           )
         end
@@ -68,7 +70,8 @@ module Poper
           should include(
             'summary_character_limit' => {
               'enabled' => true,
-              'number' => 95
+              'number' => 95,
+              'ignore_if_summary_matches' => nil
             }
           )
         end
@@ -89,7 +92,8 @@ module Poper
           should include(
             'summary_character_limit' => {
               'enabled' => false,
-              'number' => 95
+              'number' => 95,
+              'ignore_if_summary_matches' => nil
             }
           )
         end

spec/poper/regexp_spec.rb

@@ -0,0 +1,75 @@
+require 'spec_helper'
+
+module Poper
+  describe Regexp do
+    subject { described_class.new('a string') }
+
+    it { should match('Look, a string') }
+    it { should_not match('Look, another string') }
+
+    context 'when set to case-insensitive' do
+      subject { described_class.new('a string', described_class::IGNORECASE) }
+
+      it { should match('LOOK, A STRING') }
+    end
+
+    context 'when initialized with nil' do
+      subject { described_class.new(nil) }
+
+      it { should == /.^/ }
+      it { should_not match('Look, a string') }
+      it { should_not match('') }
+    end
+
+    context 'when initialized with false' do
+      subject { described_class.new(false) }
+
+      it { should == /.^/ }
+      it { should_not match('Look, a string') }
+      it { should_not match('') }
+    end
+
+    context 'when initialized with true' do
+      subject { described_class.new(true) }
+
+      it { should == // }
+      it { should match('Look, a string') }
+      it { should match('') }
+      it { should match("\n") }
+    end
+
+    context 'when intialized with an empty string' do
+      subject { described_class.new('') }
+
+      it { should == // }
+    end
+
+    context 'when initialized with a string containing special characters' do
+      subject { described_class.new('^Look') }
+
+      it { should match('Look, a string') }
+      it { should_not match('^Look, a string') }
+
+      context 'and the string has double quotes' do
+        subject { described_class.new("^Look") }
+
+        it { should match('Look, a string') }
+      end
+    end
+
+    context 'when initialized with a string containing escaped characters' do
+      subject { described_class.new('\^Look') }
+
+      it { should match('^Look, a string') }
+      it { should_not match('Look, a string') }
+
+      context 'and the string has double quotes' do
+        subject { described_class.new("\^Look") }
+
+        it { should match('Look, a string') }
+        it { should_not match('^Look, a string') }
+      end
+    end
+
+  end
+end

spec/poper/rule/character_limit_spec.rb

@@ -47,6 +47,22 @@ module Rule
           end
 
           it { should_not be_nil }
+
+          context 'when message matches ignore pattern' do
+            before do
+              File.should_receive(:exist?)
+                  .and_return(true)
+
+              YAML.should_receive(:load_file)
+                  .and_return(
+                    'character_limit' => {
+                      'ignore_if_message_matches' => 'Implement that feature'
+                    }
+                  )
+            end
+
+            it { should be_nil }
+          end
         end
 
         context 'seventy-three char last line' do
@@ -57,6 +73,22 @@ module Rule
           end
 
           it { should_not be_nil }
+
+          context 'when message matches ignore pattern' do
+            before do
+              File.should_receive(:exist?)
+                  .and_return(true)
+
+              YAML.should_receive(:load_file)
+                  .and_return(
+                    'character_limit' => {
+                      'ignore_if_message_matches' => 'Implement that feature'
+                    }
+                  )
+            end
+
+            it { should be_nil }
+          end
         end
       end
     end