Update stub RSpec syntax

spec/nc_fail_spec.rb

@@ -4,14 +4,14 @@
   let(:formatter) { NcFail.new(StringIO.new) }
 
   it 'returns a failing notification' do
-    TerminalNotifier.should_receive(:notify)
+    expect(TerminalNotifier).to receive(:notify)
 
     formatter.instance_variable_set('@failed_examples', [1])
     formatter.say('title', 'body')
   end
 
   it 'does not return a success notification when tests are passing' do
-    TerminalNotifier.should_not_receive(:notify)
+    expect(TerminalNotifier).to_not receive(:notify)
 
     formatter.say('title', 'body')
   end

spec/nc_first_fail_spec.rb

@@ -11,10 +11,10 @@
   let(:description) { 'description' }
 
   it 'notifies the first failure only' do
-    example.stub(:metadata).and_return({:full_description => description})
-    example.stub(:exception).and_return(exception)
+    allow(example).to receive(:metadata).and_return({:full_description => description})
+    allow(example).to receive(:exception).and_return(exception)
 
-    TerminalNotifier.should_receive(:notify).with("#{description}\n#{exception}",
+    expect(TerminalNotifier).to receive(:notify).with("#{description}\n#{exception}",
       :title => "#{failure} #{current_dir}: Failure"
     )
 
@@ -23,7 +23,7 @@
   end
 
   it "doesn't notify in the end if there has been any failures" do
-    TerminalNotifier.should_not_receive(:notify)
+    expect(TerminalNotifier).to_not receive(:notify)
 
     formatter.dump_summary(0.0001, 2, 1, 0)
   end

spec/nc_spec.rb

@@ -9,7 +9,7 @@
   let(:failure) { "\u26D4" }
 
   it 'returns the summary' do
-    TerminalNotifier.should_receive(:notify).with(
+    expect(TerminalNotifier).to receive(:notify).with(
       "Finished in 0.0001 seconds\n3 examples, 1 failure, 1 pending",
       :title => "#{failure} #{current_dir}: 1 failed example"
     )
@@ -18,7 +18,7 @@
   end
 
   it 'returns a failing notification' do
-    TerminalNotifier.should_receive(:notify).with(
+    expect(TerminalNotifier).to receive(:notify).with(
       "Finished in 0.0001 seconds\n1 example, 1 failure",
       :title => "#{failure} #{current_dir}: 1 failed example"
     )
@@ -27,7 +27,7 @@
   end
 
   it 'returns a success notification' do
-    TerminalNotifier.should_receive(:notify).with(
+    expect(TerminalNotifier).to receive(:notify).with(
       "Finished in 0.0001 seconds\n1 example, 0 failures",
       :title => "#{success} #{current_dir}: Success"
     )