test: specs for transparency support

.rubocop.yml

@@ -5,3 +5,18 @@ AllCops:
 
 Metrics/BlockLength:
   CountAsOne: ['array', 'hash', 'heredoc', 'method_call']
+  AllowedMethods:
+  - describe
+  - context
+  - shared_examples
+  - RSpec::Matchers.define
+
+Naming/MethodParameterName:
+  AllowedNames:
+    - x
+    - y
+    - cr
+    - x1
+    - y1
+    - x2
+    - y2

.rubocop_todo.yml

@@ -18,15 +18,6 @@ Gemspec/RequiredRubyVersion:
 Metrics/AbcSize:
   Max: 94
 
-# Offense count: 3
-# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
-# IgnoredMethods: refine
-Metrics/BlockLength:
-  AllowedMethods:
-  - describe
-  - context
-  - shared_examples
-
 # Offense count: 1
 # Configuration parameters: CountComments, CountAsOne.
 Metrics/ClassLength:
@@ -52,16 +43,6 @@ Metrics/ParameterLists:
 Metrics/PerceivedComplexity:
   Max: 17
 
-Naming/MethodParameterName:
-  AllowedNames:
-    - x
-    - y
-    - cr
-    - x1
-    - y1
-    - x2
-    - y2
-
 # Offense count: 1
 Naming/AccessorMethodName:
   Exclude:

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Support for visual image comparison in specs
 - Automated visual comparison of images in specs, also serving as a record of exact rendering behaviour
 - Development scripts for performing benchmarks
+- Basic test coverage for transparency support
 
 ### Changed
 - Extracted image operations to separate files within a dedicated module

spec/morandi_spec.rb

@@ -421,6 +421,38 @@
         expect(created_file_sizes.sort).to eq(files_in_increasing_quality_order)
       end
     end
+
+    context 'with transparent png input' do
+      let(:file_in) { 'spec/fixtures/match-with-transparency.png' }
+      let(:options) do
+        {
+          'gamma' => 1.1,
+          'fx' => 'sepia',
+          'crop' => [10, 2, 600, 840]
+        }
+      end
+
+      it 'applies transformations' do
+        process_image
+
+        expect(File).to exist(file_out)
+        expect(processed_image_type).to eq('jpeg')
+        expect(file_out).to match_reference_image('match-multiple-operations')
+      end
+
+      context 'with straighten option' do
+        # Tested explicitly, because morandi happens to handle transparency differently when using straighten
+        let(:options) { super().merge('straighten' => 2) }
+
+        it 'applies transformations' do
+          process_image
+
+          expect(File).to exist(file_out)
+          expect(processed_image_type).to eq('jpeg')
+          expect(file_out).to match_reference_image('match-multiple-operations-and-straighten')
+        end
+      end
+    end
   end
 
   context 'pixbuf processor' do

spec/support/match_reference_image.rb

@@ -42,19 +42,31 @@ class ImageDebugData
 
       attr_reader :exposed_reference_path, :exposed_tested_path, :exposed_diff_path
 
-      def initialize(name, file_type)
-        sanitised_name = name.gsub(/[^a-zA-Z0-9_-]+/, '-')
-        @output_dir = File.join(OUTPUT_ROOT, sanitised_name)
-        @exposed_reference_path = File.join(@output_dir, "reference.#{file_type}")
-        @exposed_tested_path = File.join(@output_dir, "tested.#{file_type}")
-        @exposed_diff_path = File.join(@output_dir, 'diff.png')
+      def initialize(name)
+        @name = name
       end
 
-      def expose_from(reference_path:, tested_path:, diff_path:)
-        FileUtils.mkdir_p(@output_dir)
-        FileUtils.cp(tested_path, @exposed_tested_path)
-        FileUtils.cp(reference_path, @exposed_reference_path)
-        FileUtils.cp(diff_path, @exposed_diff_path)
+      def expose_from(file_type:, tested_path: nil, reference_path: nil, diff_path: nil)
+        sanitised_name = @name.gsub(/[^a-zA-Z0-9_-]+/, '-')
+        output_dir = File.join(OUTPUT_ROOT, sanitised_name)
+        FileUtils.mkdir_p(output_dir)
+
+        if reference_path
+          @exposed_reference_path = File.join(output_dir, "reference.#{file_type}")
+          FileUtils.cp(reference_path, @exposed_reference_path)
+        end
+
+        if tested_path
+          @exposed_tested_path = File.join(output_dir, "tested.#{file_type}")
+          FileUtils.cp(tested_path, @exposed_tested_path)
+        end
+
+        if diff_path
+          @exposed_diff_path = File.join(output_dir, 'diff.png')
+          FileUtils.cp(diff_path, @exposed_diff_path)
+        end
+
+        true
       end
     end
   end
@@ -63,7 +75,18 @@ def expose_from(reference_path:, tested_path:, diff_path:)
 RSpec::Matchers.define :match_reference_image do |reference_name, file_type: 'jpg', tolerance: 0|
   reference_path = File.join('spec/fixtures/reference_images', "#{reference_name}.#{file_type}")
 
+  def debug_data
+    metadata = RSpec.current_example.metadata
+    spec_name = "#{metadata[:absolute_file_path].split('/spec/').last}:#{metadata[:scoped_id]}"
+    @debug_data ||= Morandi::SpecSupport::ImageDebugData.new(spec_name)
+  end
+
   match do |tested_path|
+    if File.file?(tested_path) && !File.file?(reference_path)
+      debug_data.expose_from(tested_path: tested_path, file_type: file_type)
+      return false
+    end
+
     tmp_diff = Tempfile.new('test-diff')
     comparison = Morandi::SpecSupport::ImageComparison.new(reference_path: reference_path,
                                                            tested_path: tested_path,
@@ -72,25 +95,35 @@ def expose_from(reference_path:, tested_path:, diff_path:)
     @normalized_mean_error = comparison.normalized_mean_error
     return true if @normalized_mean_error <= tolerance
 
-    metadata = RSpec.current_example.metadata
-    spec_name = "#{metadata[:absolute_file_path].split('/spec/').last}:#{metadata[:scoped_id]}"
-    @debug_data = Morandi::SpecSupport::ImageDebugData.new(spec_name, file_type)
-
-    @debug_data.expose_from(reference_path: reference_path, tested_path: tested_path, diff_path: tmp_diff.path)
+    debug_data.expose_from(reference_path: reference_path,
+                           tested_path: tested_path,
+                           diff_path: tmp_diff.path,
+                           file_type: file_type)
     false
   ensure
-    tmp_diff.close!
+    tmp_diff&.close!
   end
 
   failure_message do
-    <<~TXT
-      The provided image and reference image do not match (error: #{@normalized_mean_error}, tolerance: #{tolerance})
-      EXPECTED: #{@debug_data.exposed_reference_path}
-      ACTUAL: #{@debug_data.exposed_tested_path}
-      DIFF: #{@debug_data.exposed_diff_path}
-
-      After manually confirming that the difference is expected, run:
-      cp #{@debug_data.exposed_tested_path} #{reference_path}
-    TXT
+    if debug_data.exposed_reference_path
+      <<~TXT
+        The provided image and reference image do not match (error: #{@normalized_mean_error}, tolerance: #{tolerance})
+        EXPECTED: #{debug_data.exposed_reference_path}
+        ACTUAL: #{debug_data.exposed_tested_path}
+        DIFF: #{debug_data.exposed_diff_path}
+
+        After manually confirming that the difference is expected, run:
+        cp #{debug_data.exposed_tested_path} #{reference_path}
+
+      TXT
+    else
+      <<~TXT
+        The provided reference image does not exist.
+
+        If there is no typo and tested image is valid, reference can be created with:
+        cp #{debug_data.exposed_tested_path} #{reference_path}
+
+      TXT
+    end
   end
 end