Simplify matching logic in tests

Simplify matching logic by adding a custom matcher which
handles the task of normalisation of object IDs instead of
calling gsub many times throughout the test code.

This allows our tests to focus more on what needs to be tested
instead obfuscating the tests with logic unrelated to what
the test is trying to cover.

It also allows making the normalisation code more robust so
there is less chance of an accidental match or typo slipping
in.

The change also replaces the arbitary default object IDs with a
string that makes it very obvious that it is just a placeholder.

spec/ext/mongo_mapper_spec.rb

@@ -36,9 +36,9 @@ RSpec.describe "AwesomePrint/MongoMapper", skip: ->{ !ExtVerifier.has_mongo_mapp
 
       if MongoMapper::Version >= "0.13"
         str = <<-EOS.strip
-#<MongoUser:0x01234567
+#<MongoUser:placeholder_id
     @__mm_default_keys = [
-        [0] #<MongoMapper::Plugins::Keys::Key:0x01234567
+        [0] #<MongoMapper::Plugins::Keys::Key:placeholder_id
             @dynamic = false,
             @embeddable = false,
             @has_default = true,
@@ -55,7 +55,7 @@ RSpec.describe "AwesomePrint/MongoMapper", skip: ->{ !ExtVerifier.has_mongo_mapp
         >
     ],
     @__mm_keys = {
-               "_id" => #<MongoMapper::Plugins::Keys::Key:0x01234567
+               "_id" => #<MongoMapper::Plugins::Keys::Key:placeholder_id
             @dynamic = false,
             @embeddable = false,
             @has_default = true,
@@ -70,7 +70,7 @@ RSpec.describe "AwesomePrint/MongoMapper", skip: ->{ !ExtVerifier.has_mongo_mapp
             },
             attr_accessor :type = ObjectId < Object
         >,
-        "first_name" => #<MongoMapper::Plugins::Keys::Key:0x01234567
+        "first_name" => #<MongoMapper::Plugins::Keys::Key:placeholder_id
             @dynamic = false,
             @embeddable = false,
             @has_default = false,
@@ -82,7 +82,7 @@ RSpec.describe "AwesomePrint/MongoMapper", skip: ->{ !ExtVerifier.has_mongo_mapp
             attr_accessor :options = {},
             attr_accessor :type = String < Object
         >,
-         "last_name" => #<MongoMapper::Plugins::Keys::Key:0x01234567
+         "last_name" => #<MongoMapper::Plugins::Keys::Key:placeholder_id
             @dynamic = false,
             @embeddable = false,
             @has_default = false,
@@ -113,7 +113,7 @@ RSpec.describe "AwesomePrint/MongoMapper", skip: ->{ !ExtVerifier.has_mongo_mapp
         EOS
       else
         str = <<-EOS.strip
-#<MongoUser:0x01234567
+#<MongoUser:placeholder_id
     @_new = true,
     attr_accessor :first_name = "Al",
     attr_accessor :last_name = "Capone",
@@ -126,8 +126,7 @@ RSpec.describe "AwesomePrint/MongoMapper", skip: ->{ !ExtVerifier.has_mongo_mapp
 >
         EOS
       end
-      out.gsub!(/0x([a-f\d]+)/, "0x01234567")
+      expect(out).to be_similar_to(str)
-      expect(out).to eq(str)
     end
 
     it "should print the class" do
@@ -193,14 +192,12 @@ class Parent < Object {
         parent = Parent.new(:name => 'test')
         out = @ap.send(:awesome, parent)
         str = <<-EOS.strip
-#<Parent:0x01234567> {
+#<Parent:placeholder_id> {
-     "_id" => BSON::ObjectId('4d9183739a546f6806000001'),
+     "_id" => placeholder_bison_id,
     "name" => "test"
 }
         EOS
-        out.gsub!(/'([\w]+){23}'/, "'4d9183739a546f6806000001'")
+        expect(out).to be_similar_to(str)
-        out.gsub!(/0x([a-f\d]+)/, "0x01234567")
-        expect(out).to eq(str)
       end
     end
 
@@ -224,16 +221,14 @@ class Parent < Object {
         parent = Parent.new(:name => 'test')
         out = @ap.send(:awesome, parent)
         str = <<-EOS.strip
-#<Parent:0x01234567> {
+#<Parent:placeholder_id> {
-        "_id" => BSON::ObjectId('4d9183739a546f6806000001'),
+        "_id" => placeholder_bison_id,
        "name" => "test",
       "child" => embeds one Child,
     "sibling" => one Sibling
 }
         EOS
-        out.gsub!(/'([\w]+){23}'/, "'4d9183739a546f6806000001'")
+        expect(out).to be_similar_to(str)
-        out.gsub!(/0x([a-f\d]+)/, "0x01234567")
-        expect(out).to eq(str)
       end
     end
 
@@ -251,19 +246,17 @@ class Parent < Object {
         parent = Parent.new(:name => 'test', :child => Child.new(:data => 5))
         out = @ap.send(:awesome, parent)
         str = <<-EOS.strip
-#<Parent:0x01234567> {
+#<Parent:placeholder_id> {
-        "_id" => BSON::ObjectId('4d9183739a546f6806000001'),
+        "_id" => placeholder_bison_id,
        "name" => "test",
-      "child" => embedded #<Child:0x01234567> {
+      "child" => embedded #<Child:placeholder_id> {
-         "_id" => BSON::ObjectId('4d9183739a546f6806000001'),
+         "_id" => placeholder_bison_id,
         "data" => 5
     },
     "sibling" => one Sibling
 }
         EOS
-        out.gsub!(/'([\w]+){23}'/, "'4d9183739a546f6806000001'")
+        expect(out).to be_similar_to(str)
-        out.gsub!(/0x([a-f\d]+)/, "0x01234567")
-        expect(out).to eq(str)
       end
     end
   end

spec/ext/mongoid_spec.rb

@@ -29,14 +29,13 @@ RSpec.describe "AwesomePrint/Mongoid", skip: ->{ !ExtVerifier.has_mongoid? }.cal
 
     object_id = user.id.inspect
     str = <<-EOS.strip
-#<MongoUser:0x01234567> {
+#<MongoUser:placeholder_id> {
            :_id => #{object_id},
     :first_name => "Al",
      :last_name => "Capone"
 }
     EOS
-    out.gsub!(/0x([a-f\d]+)/, "0x01234567")
+    expect(out).to be_similar_to(str)
-    expect(out).to eq(str)
   end
 
   it "should print the class" do

spec/ext/ripple_spec.rb

@@ -28,8 +28,8 @@ RSpec.describe 'AwesomePrint/Ripple', skip: ->{ !ExtVerifier.has_ripple? }.call
     user = RippleUser.new :_id => "12345", :first_name => "Al", :last_name => "Capone"
     out = @ap.send :awesome, user
 
-    expect(out.gsub(/0x([a-f\d]+)/, "0x01234567")).to eq <<-EOS.strip
+    expect(out).to be_similar_to <<-EOS.strip
-#<RippleUser:0x01234567> {
+#<RippleUser:placeholder_id> {
            :_id => "12345",
     :first_name => "Al",
      :last_name => "Capone"

spec/objects_spec.rb

@@ -24,13 +24,13 @@ RSpec.describe "Objects" do
       hello = Hello.new
       out = hello.ai(:plain => true, :raw => true)
       str = <<-EOS.strip
-#<Hello:0x01234567
+#<Hello:placeholder_id
     attr_accessor :dabra = 3,
     attr_reader :abra = 1,
     attr_writer :ca = 2
 >
 EOS
-      expect(out.gsub(/0x([a-f\d]+)/, "0x01234567")).to eq(str)
+      expect(out).to be_similar_to(str)
       expect(hello.ai(:plain => true, :raw => false)).to eq(hello.inspect)
     end
 
@@ -44,13 +44,13 @@ EOS
       hello = Hello.new
       out = hello.ai(:plain => true, :raw => true)
       str = <<-EOS.strip
-#<Hello:0x01234567
+#<Hello:placeholder_id
     @abra = 1,
     @ca = 2,
     @dabra = 3
 >
 EOS
-      expect(out.gsub(/0x([a-f\d]+)/, "0x01234567")).to eq(str)
+      expect(out).to be_similar_to(str)
       expect(hello.ai(:plain => true, :raw => false)).to eq(hello.inspect)
     end
 
@@ -69,7 +69,7 @@ EOS
       hello = Hello.new
       out = hello.ai(:plain => true, :raw => true)
       str = <<-EOS.strip
-#<Hello:0x01234567
+#<Hello:placeholder_id
     @doo = 1,
     @dooby = 2,
     @scooby = 3,
@@ -78,7 +78,7 @@ EOS
     attr_writer :ca = 2
 >
 EOS
-      expect(out.gsub(/0x([a-f\d]+)/, "0x01234567")).to eq(str)
+      expect(out).to be_similar_to(str)
       expect(hello.ai(:plain => true, :raw => false)).to eq(hello.inspect)
     end
 
@@ -96,13 +96,13 @@ EOS
       hello = Hello.new
       out = hello.ai(:raw => true)
       str = <<-EOS.strip
-#<Hello:0x01234567
+#<Hello:placeholder_id
     \e[0;36m@dabra\e[0m\e[0;37m = \e[0m\e[1;34m3\e[0m,
     \e[1;36mattr_reader\e[0m \e[0;35m:abra\e[0m\e[0;37m = \e[0m\e[1;34m1\e[0m,
     \e[1;36mattr_writer\e[0m \e[0;35m:ca\e[0m\e[0;37m = \e[0m\e[1;34m2\e[0m
 >
 EOS
-      expect(out.gsub(/0x([a-f\d]+)/, "0x01234567")).to eq(str)
+      expect(out).to be_similar_to(str)
       expect(hello.ai(:plain => true, :raw => false)).to eq(hello.inspect)
     end
 
@@ -120,9 +120,9 @@ EOS
       hello = Hello.new
       out = hello.ai(:multiline => false, :plain => true, :raw => true)
       str = <<-EOS.strip
-#<Hello:0x01234567 @dabra = 3, attr_reader :abra = 1, attr_writer :ca = 2>
+#<Hello:placeholder_id @dabra = 3, attr_reader :abra = 1, attr_writer :ca = 2>
 EOS
-      expect(out.gsub(/0x([a-f\d]+)/, "0x01234567")).to eq(str)
+      expect(out).to be_similar_to(str)
       expect(hello.ai(:plain => true, :raw => false)).to eq(hello.inspect)
     end
   end

spec/spec_helper.rb

@@ -47,6 +47,26 @@ RSpec.configure do |config|
   end
 end
 
+# This matcher handles the normalization of objects to replace non deterministic
+# parts (such as object IDs) with simple placeholder strings before doing a
+# comparison with a given string. It's important that this method only matches
+# a string which strictly conforms to the expected object ID format.
+RSpec::Matchers.define :be_similar_to do |expected|
+  match do |actual|
+    @actual = normalize_object_strings(actual)
+    values_match? expected, @actual
+  end
+
+  diffable
+end
+
+# Override the Object IDs with a placeholder so that we are only checking
+# that an ID is present and not that it matches a certain value. This is
+# necessary as the Object IDs are not deterministic.
+def normalize_object_strings(str)
+  str.gsub(/#<(.*?):0x[a-f\d]+/, '#<\1:placeholder_id')
+end
+
 def stub_dotfile!
   dotfile = File.join(ENV["HOME"], ".aprc")
   expect(File).to receive(:readable?).at_least(:once).with(dotfile).and_return(false)