Use YAML.to_json instead of YAML.dump

We're not using any features of YAML outside of
dictionaries and lists (hashes and arrays), so why not
let our data be parseable by YAML _and_ JSON?

lib/metric_fu/reporting/result.rb

@@ -18,7 +18,7 @@ class Result
     #   A YAML object containing the results of the result generation
     #   process
     def as_yaml
-      result_hash.to_yaml
+      YAML.to_json(result_hash)
     end
 
     def per_file_data

spec/metric_fu/formatter/yaml_spec.rb

@@ -50,8 +50,18 @@
       out = MetricFu::Utility.capture_output {
         MetricFu::Formatter::YAML.new(output: @output).finish
       }
-      expect(out).to include ":#{@metric1}:"
-      expect(out).to include ":#{@metric2}:"
+      expected_output = YAML.to_json(
+        "#{@metric1}" => {
+          "total_violations" => 0,
+          "violations" => {},
+        },
+        "#{@metric2}" => {
+          "files" => [],
+          "classes" => [],
+          "methods" => [],
+        }
+      )
+      expect(out).to eq(expected_output)
     end
   end
 

spec/metric_fu/reporting/result_spec.rb

@@ -16,17 +16,15 @@
 
   describe "#as_yaml" do
     it "should call #result_hash" do
-      result_hash = double("result_hash")
-      expect(result_hash).to receive(:to_yaml)
-
-      expect(@result).to receive(:result_hash).and_return(result_hash)
-      @result.as_yaml
+      result_hash =  { "hi" => "there" }
+      @result.result_hash.update(result_hash)
+      yaml = @result.as_yaml
+      expected_yaml = '{"hi": "there"}' << "\n"
+      expect(yaml).to eq(expected_yaml)
+      expect(JSON.load(yaml)).to eq(result_hash)
     end
   end
 
-  describe "#result_hash" do
-  end
-
   describe "#add" do
     it "should add a passed hash to the result_hash instance variable" do
       result_type = double("result_type")