Address some RuboCop warnings (#112)

* RuboCop: RSpec/MultipleExpectations

* RuboCop: Style/StringLiteralsInInterpolation

* RuboCop: RSpec/ReceiveMessages

lib/svgeez/elements/symbol_element.rb

@@ -10,7 +10,7 @@ def initialize(file_path, file_id)
 
       def build
         File.read(@file_path).match(%r{^<svg\s*?(?<attributes>.*?)>(?<content>.*?)</svg>}m) do |matches|
-          %(<symbol #{element_attributes(matches[:attributes]).sort.join(" ")}>#{element_contents(matches[:content])}</symbol>)
+          "<symbol #{element_attributes(matches[:attributes]).sort.join(' ')}>#{element_contents(matches[:content])}</symbol>"
         end
       end
 

spec/lib/svgeez/builder_build_spec.rb

@@ -19,14 +19,14 @@
       allow(File).to receive(:directory?).and_return(false)
     end
 
-    it "logs an error" do
+    it "logs an error", :aggregate_failures do
       expect { described_class.new.build }.to raise_error(SystemExit)
       expect(logger).to have_received(:error).with("Provided `source` folder does not exist.")
     end
   end
 
   context "when @source and @destination are the same" do
-    it "logs an error" do
+    it "logs an error", :aggregate_failures do
       builder = described_class.new(
         "source" => "./foo",
         "destination" => "./foo"
@@ -37,7 +37,7 @@
     end
   end
 
-  context "when @destination is nested within @source" do
+  context "when @destination is nested within @source", :aggregate_failures do
     it "logs an error" do
       builder = described_class.new(
         "source" => "./foo",
@@ -70,14 +70,14 @@
 
       allow(file).to receive(:write)
 
-      file_paths = %w[facebook github heart skull twitter].map { |i| "./spec/fixtures/icons/#{i}.svg" }
-
-      allow(source).to receive(:file_paths).and_return(file_paths)
-      allow(source).to receive(:folder_path).and_return(File.expand_path(source_folder_path))
+      allow(source).to receive_messages(
+        file_paths: %w[facebook github heart skull twitter].map { |i| "./spec/fixtures/icons/#{i}.svg" },
+        folder_path: File.expand_path(source_folder_path)
+      )
     end
 
     context "when @svgo is not specified" do
-      it "writes a file" do
+      it "writes a file", :aggregate_failures do
         described_class.new(
           "source" => source_folder_path,
           "destination" => "./spec/fixtures/icons.svg"
@@ -89,14 +89,14 @@
     end
 
     context "when @svgo is specified" do
-      it "writes a file" do
+      it "writes a file", :aggregate_failures do
         described_class.new(
           "source" => source_folder_path,
           "destination" => "./spec/fixtures/icons-svgo.svg",
           "svgo" => true
         ).build
 
-        expect(file).to have_received(:write).with(%(#{File.read("./spec/fixtures/icons-svgo.svg")}\n))
+        expect(file).to have_received(:write).with("#{File.read('./spec/fixtures/icons-svgo.svg')}\n")
         expect(logger).to have_received(:info).exactly(:twice)
       end
     end