From 68da0456ead0713a06c8b8fed3a8516c67c9f4c3 Mon Sep 17 00:00:00 2001
From: Markus Schirp <mbj@schirp-dso.com>
Date: Tue, 4 Dec 2018 14:28:49 +0000
Subject: [PATCH] Change fail fast computation to reduce scope

* All state to compute #stop? is available on the result already, there
  is no need to peek into the structure from the outside.
---
 lib/mutant/result.rb                |  8 +++++
 lib/mutant/runner/sink.rb           |  2 +-
 spec/unit/mutant/result/env_spec.rb | 55 ++++++++++++++++++++++++++---
 3 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/lib/mutant/result.rb b/lib/mutant/result.rb
index 8fb15c4e..b3e449fd 100644
--- a/lib/mutant/result.rb
+++ b/lib/mutant/result.rb
@@ -108,6 +108,14 @@ module Mutant
         env.subjects.length
       end
 
+      # Test if processing needs to stop
+      #
+      # @return [Boolean]
+      #
+      def stop?
+        env.config.fail_fast && !subject_results.all?(&:success?)
+      end
+
     end # Env
 
     # Test result
diff --git a/lib/mutant/runner/sink.rb b/lib/mutant/runner/sink.rb
index dd717722..041c00df 100644
--- a/lib/mutant/runner/sink.rb
+++ b/lib/mutant/runner/sink.rb
@@ -29,7 +29,7 @@ module Mutant
       #
       # @return [Boolean]
       def stop?
-        env.config.fail_fast && !status.subject_results.all?(&:success?)
+        status.stop?
       end
 
       # Handle mutation finish
diff --git a/spec/unit/mutant/result/env_spec.rb b/spec/unit/mutant/result/env_spec.rb
index 75cc994f..97104ee5 100644
--- a/spec/unit/mutant/result/env_spec.rb
+++ b/spec/unit/mutant/result/env_spec.rb
@@ -5,13 +5,16 @@ RSpec.describe Mutant::Result::Env do
     described_class.new(
       runtime:         instance_double(Float),
       env:             env,
-      subject_results: [subject_result]
+      subject_results: subject_results
     )
   end
 
+  let(:subject_results) { [subject_result] }
+
   let(:env) do
     instance_double(
       Mutant::Env,
+      config:    instance_double(Mutant::Config, fail_fast: fail_fast),
       subjects:  [instance_double(Mutant::Subject)],
       mutations: [instance_double(Mutant::Mutation)]
     )
@@ -22,12 +25,14 @@ RSpec.describe Mutant::Result::Env do
       Mutant::Result::Subject,
       amount_mutation_results: results,
       amount_mutations_killed: killed,
-      success?:                true
+      success?:                subject_success?
     )
   end
 
-  let(:results) { 1 }
-  let(:killed)  { 0 }
+  let(:fail_fast)        { false }
+  let(:killed)           { 0     }
+  let(:results)          { 1     }
+  let(:subject_success?) { true }
 
   describe '#success?' do
     subject { object.success? }
@@ -81,4 +86,46 @@ RSpec.describe Mutant::Result::Env do
 
     it { should eql(1) }
   end
+
+  describe '#stop?' do
+    subject { object.stop? }
+
+    context 'without fail fast' do
+      context 'on empty subjects' do
+        let(:subject_results) { [] }
+
+        it { should be(false) }
+      end
+
+      context 'on failed subject' do
+        let(:subject_success?) { false }
+
+        it { should be(false) }
+      end
+
+      context 'on successful subject' do
+        it { should be(false) }
+      end
+    end
+
+    context 'with fail fast' do
+      let(:fail_fast) { true }
+
+      context 'on empty subjects' do
+        let(:subject_results) { [] }
+
+        it { should be(false) }
+      end
+
+      context 'on failed subject' do
+        let(:subject_success?) { false }
+
+        it { should be(true) }
+      end
+
+      context 'on successful subject' do
+        it { should be(false) }
+      end
+    end
+  end
 end