Add specification for runner isolation errors

lib/mutant/runner.rb

@@ -121,13 +121,16 @@ module Mutant
     # @api private
     #
     def run_mutation_test(mutation, test)
+      time = Time.now
       config.isolation.call do
         mutation.insert
         test.run
       end.update(test: test, mutation: mutation)
-    rescue Isolation::Error
+    rescue Isolation::Error => exception
       Result::Test.new(
         test:     test,
+        mutation: mutation,
+        runtime:  Time.now - time,
         output:   exception.message,
         passed:   false
       )

spec/unit/mutant/runner_spec.rb

@@ -4,7 +4,7 @@ describe Mutant::Runner do
   let(:object) { described_class.new(env) }
 
   let(:reporter) { Mutant::Reporter::Trace.new                        }
-  let(:config)   { Mutant::Config::DEFAULT.update(reporter: reporter) }
+  let(:config)   { Mutant::Config::DEFAULT.update(reporter: reporter, isolation: Mutant::Isolation::None) }
   let(:subjects) { [subject_a, subject_b]                             }
 
   class Double
@@ -63,12 +63,6 @@ describe Mutant::Runner do
     allow(Time).to receive(:now).and_return(time)
   end
 
-  describe '#result' do
-    subject { object.result }
-
-    its(:env)             { should be(env)                       }
-    its(:subject_results) { should eql(expected_subject_results) }
-
   let(:expected_subject_results) do
     [
       Mutant::Result::Subject.new(
@@ -94,5 +88,40 @@ describe Mutant::Runner do
       )
     ]
   end
+
+  describe '#result' do
+    context 'on normal execution' do
+      subject { object.result }
+
+      its(:env)             { should be(env)                       }
+      its(:subject_results) { should eql(expected_subject_results) }
+    end
+
+    context 'when isolation raises error' do
+      subject { object.result }
+
+      its(:env)             { should be(env)                       }
+      its(:subject_results) { should eql(expected_subject_results) }
+
+      before do
+        expect(Mutant::Isolation::None).to receive(:call).and_raise(Mutant::Isolation::Error.new('test-exception-message')).twice
+
+        expect(Mutant::Result::Test).to receive(:new).with(
+          test:     test_a1,
+          mutation: mutation_a1,
+          runtime:  0.0,
+          output:   'test-exception-message',
+          passed:   false
+        ).and_return(test_report_a1)
+        expect(Mutant::Result::Test).to receive(:new).with(
+          test:     test_a1,
+          mutation: mutation_a2,
+          runtime:  0.0,
+          output:   'test-exception-message',
+          passed:   false
+        ).and_return(test_report_a1)
+      end
+
+    end
   end
 end