Fixed functionality of #from_file within non-main Ractors, wvanbergen…

…#170

CHANGELOG.rdoc

@@ -7,6 +7,8 @@ The file documents the changes to this library over the different versions.
 
 === Unreleased changes
 
+- Fixed functionality of #from_file within non-main Ractors.
+
 === 1.4.0 - 2020-12-28
 
 - Add compatibility for Ruby 3.0. 

lib/chunky_png.rb

@@ -143,7 +143,7 @@ class UnitsUnknown < ChunkyPNG::Exception
   # Null-byte, with the encoding set correctly to ASCII-8BIT (binary) in Ruby 1.9.
   # @return [String] A binary string, consisting of one NULL-byte.
   # @private
-  EXTRA_BYTE = "\0".b
+  EXTRA_BYTE = "\0".b.freeze
 end
 
 require "chunky_png/version"

lib/chunky_png/chunk.rb

@@ -467,6 +467,6 @@ def content
       "zTXt" => CompressedText,
       "iTXt" => InternationalText,
       "pHYs" => Physical,
-    }
+    }.freeze
   end
 end

lib/chunky_png/color.rb

@@ -888,7 +888,7 @@ def euclidean_distance_rgba(pixel_after, pixel_before)
       whitesmoke: 0xf5f5f500,
       yellow: 0xffff0000,
       yellowgreen: 0x9acd3200,
-    }
+    }.freeze
 
     # Gets a color value based on a HTML color name.
     #

spec/chunky_png/canvas_spec.rb

@@ -237,4 +237,9 @@
       expect(subject.inspect).to eql "<ChunkyPNG::Canvas 1x1 [\n\t[#ffffffff]\n]>"
     end
   end
+
+  it "should behave properly with the new Ruby 3.0 Ractors" do
+    img = Ractor.new { ChunkyPNG::Canvas.from_file(resource_file("operations.png")) }.take
+    expect(img).to eql ChunkyPNG::Canvas.from_file(resource_file("operations.png"))
+  end
 end