use monotonic time

see ruby-concurrency/concurrent-ruby#256 for reasons

lib/ci/reporter/monotonic_time.rb

@@ -0,0 +1,26 @@
+module CI
+  module Reporter
+    module MonotonicTime
+      module_function
+
+      if defined?(Process::CLOCK_MONOTONIC)
+        def time_in_nanoseconds
+          Process.clock_gettime(Process::CLOCK_MONOTONIC, :nanosecond)
+        end
+      elsif (defined?(RUBY_ENGINE) ? RUBY_ENGINE : 'ruby') == 'jruby'
+        def time_in_nanoseconds
+          java.lang.System.nanoTime()
+        end
+      else
+        def time_in_nanoseconds
+          t = Time.now
+          t.to_i * 10 ** 9 + t.nsec
+        end
+      end
+
+      def time_in_seconds
+        time_in_nanoseconds / 10 ** 9.0
+      end
+    end
+  end
+end

lib/ci/reporter/test_suite.rb

@@ -1,6 +1,7 @@
 require 'time'
 require 'builder'
 require 'ci/reporter/output_capture'
+require 'ci/reporter/monotonic_time'
 
 module CI
   module Reporter
@@ -38,7 +39,8 @@ def initialize(name)
 
       # Starts timing the test suite.
       def start
-        @start = Time.now
+        @start_time = Time.now
+        @start = MonotonicTime.time_in_seconds
         unless ENV['CI_CAPTURE'] == "off"
           @capture_out = OutputCapture.wrap($stdout) {|io| $stdout = io }
           @capture_err = OutputCapture.wrap($stderr) {|io| $stderr = io }
@@ -48,8 +50,8 @@ def start
       # Finishes timing the test suite.
       def finish
         self.tests = testcases.size
-        self.time = Time.now - @start
-        self.timestamp = @start.iso8601
+        self.time = MonotonicTime.time_in_seconds - @start
+        self.timestamp = @start_time.iso8601
         self.failures = testcases.map(&:failure_count).reduce(&:+)
         self.errors = testcases.map(&:error_count).reduce(&:+)
         self.skipped = testcases.count(&:skipped?)
@@ -93,12 +95,12 @@ def initialize(*args)
 
       # Starts timing the test.
       def start
-        @start = Time.now
+        @start = MonotonicTime.time_in_seconds
       end
 
       # Finishes timing the test.
       def finish
-        self.time = Time.now - @start
+        self.time = MonotonicTime.time_in_seconds - @start
       end
 
       # Returns non-nil if the test failed.