issue #510: use subject in monotonic_time_spec

spec/lib/listen/monotonic_time_spec.rb

@@ -5,15 +5,17 @@
 RSpec.describe Listen::MonotonicTime do
   context 'module methods' do
     describe '.now' do
+      subject { described_class.now }
       let(:tick_count) { 0.123 }
+
       context 'when CLOCK_MONOTONIC defined' do
         before do
           stub_const('Process::CLOCK_MONOTONIC', 10)
         end
 
         it 'returns the CLOCK_MONOTONIC tick count' do
           expect(Process).to receive(:clock_gettime).with(Process::CLOCK_MONOTONIC).and_return(tick_count)
-          expect(described_class.now).to eq(tick_count)
+          expect(subject).to eq(tick_count)
         end
       end
 
@@ -25,7 +27,7 @@
 
         it 'returns the floating point Time.now' do
           expect(Process).to receive(:clock_gettime).with(Process::CLOCK_MONOTONIC_RAW).and_return(tick_count)
-          expect(described_class.now).to eq(tick_count)
+          expect(subject).to eq(tick_count)
         end
       end
 
@@ -40,7 +42,7 @@
         it 'returns the floating point Time.now' do
           expect(Time).to receive(:now).and_return(now)
           expect(now).to receive(:to_f).and_return(tick_count)
-          expect(described_class.now).to eq(tick_count)
+          expect(subject).to eq(tick_count)
         end
       end
     end