[Fix rubocop#6132] Fix a false negative for Naming/FileName

Fixes rubocop#6132.

### Summary

This PR fixes a false negative for `Naming/FileName`
when `Include` of `AllCops` is the default setting.

The important change in this PR is below.

```diff
diff --git a/lib/rubocop/cop/naming/file_name.rb
b/lib/rubocop/cop/naming/file_name.rb
index a025a73b7..be3f1c5aa 100644
--- a/lib/rubocop/cop/naming/file_name.rb
+++ b/lib/rubocop/cop/naming/file_name.rb
@@ -32,7 +32,7 @@ module RuboCop

         def investigate(processed_source)
           file_path = processed_source.file_path
-          return if config.file_to_include?(file_path)
+          return if config.file_to_exclude?(file_path)
```

The problem is that the target to be excluded was
`Include` instead of `Exclude`.

Also this PR adds the `RuboCop::Config#allowed_camel_case_file?`
method to judge ignoring `Gemfile`, `Rakefile`, etc
described in` Include`.

### Other Information

This false negative was noticed by adding `**/*.rb` to
config/default.yml at rubocop#5882.

https://github.com/rubocop-hq/rubocop/pull/5882/files#diff-e93280b3b31a6438c533a5f3232340d8R18

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### Bug fixes
+
+* [#6132](https://github.com/rubocop-hq/rubocop/issues/6132): Fix a false negative for `Naming/FileName` when `Include` of `AllCops` is the default setting. ([@koic][])
+
 ### Changes
 
 * [#6137](https://github.com/rubocop-hq/rubocop/pull/6137): Allow `db` to allowed names of `Naming/UncommunicativeMethodParamName` cop in default config. ([@mkenyon][])

lib/rubocop/config.rb

@@ -373,8 +373,20 @@ def file_to_include?(file)
       absolute_file_path = File.expand_path(file)
 
       patterns_to_include.any? do |pattern|
-        match_path?(pattern, relative_file_path) ||
-          match_path?(pattern, absolute_file_path)
+        if block_given?
+          yield pattern, relative_file_path, absolute_file_path
+        else
+          match_path?(pattern, relative_file_path) ||
+            match_path?(pattern, absolute_file_path)
+        end
+      end
+    end
+
+    def allowed_camel_case_file?(file)
+      file_to_include?(file) do |pattern, relative_path, absolute_path|
+        pattern.to_s =~ /[A-Z]/ &&
+          (match_path?(pattern, relative_path) ||
+           match_path?(pattern, absolute_path))
       end
     end
 
@@ -396,11 +408,11 @@ def file_to_exclude?(file)
     end
 
     def patterns_to_include
-      for_all_cops['Include']
+      for_all_cops['Include'] || []
     end
 
     def patterns_to_exclude
-      for_all_cops['Exclude']
+      for_all_cops['Exclude'] || []
     end
 
     def path_relative_to_config(path)

lib/rubocop/cop/naming/file_name.rb

@@ -32,7 +32,8 @@ class FileName < Cop
 
         def investigate(processed_source)
           file_path = processed_source.file_path
-          return if config.file_to_include?(file_path)
+          return if config.file_to_exclude?(file_path) ||
+                    config.allowed_camel_case_file?(file_path)
 
           for_bad_filename(file_path) do |range, msg|
             add_offense(nil, location: range, message: msg)

spec/rubocop/config_spec.rb

@@ -395,6 +395,7 @@
 
   describe '#file_to_exclude?' do
     before { $stderr = StringIO.new }
+
     after { $stderr = STDERR }
 
     let(:hash) do
@@ -433,6 +434,32 @@
     end
   end
 
+  describe '#allowed_camel_case_file?' do
+    subject { configuration.allowed_camel_case_file?(file_path) }
+
+    let(:hash) do
+      {
+        'AllCops' => {
+          'Include' => ['**/Gemfile']
+        }
+      }
+    end
+
+    context 'when the passed path matches allowed camel case patterns ' \
+            'to include' do
+      let(:file_path) { '/home/foo/project/Gemfile' }
+
+      it { is_expected.to be true }
+    end
+
+    context 'when the passed path does not match allowed camel case patterns ' \
+            'to include' do
+      let(:file_path) { '/home/foo/project/testCase' }
+
+      it { is_expected.to be false }
+    end
+  end
+
   describe '#patterns_to_include' do
     subject(:patterns_to_include) do
       configuration = described_class.new(hash, loaded_path)
@@ -527,6 +554,7 @@
       let(:hash) { { 'AllCops' => { 'Includes' => [] } } }
 
       before { $stderr = StringIO.new }
+
       after { $stderr = STDERR }
 
       it 'prints a warning message for the loaded path' do

spec/rubocop/cop/naming/file_name_spec.rb

@@ -18,7 +18,7 @@
     }
   end
 
-  let(:includes) { [] }
+  let(:includes) { ['**/*.rb'] }
   let(:source) { 'print 1' }
   let(:processed_source) { parse_source(source) }