From 88b238b1bb3224e402918d3c12574080e5bcc091 Mon Sep 17 00:00:00 2001
From: Michael Grosser <michael@grosser.it>
Date: Wed, 14 Feb 2018 17:49:29 -0800
Subject: [PATCH] branch coverage

---
 .travis.yml              |  2 ++
 Readme.md                |  5 +++--
 lib/single_cov.rb        | 34 +++++++++++++++++++++++++++++++---
 specs/single_cov_spec.rb | 35 ++++++++++++++++++++++++++++++-----
 4 files changed, 66 insertions(+), 10 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 17c5888..e4a3d11 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,6 @@
 bundler_args: ""
+branches:
+  only: master
 rvm:
   - 2.0
   - 2.1
diff --git a/Readme.md b/Readme.md
index 8c61383..b1c4077 100644
--- a/Readme.md
+++ b/Readme.md
@@ -4,6 +4,7 @@ Actionable code coverage.
  - Get actionable feedback on every successful test run
  - Only 2-5% runtime overhead on small files compared to 50% for `SimpleCov`
  - No more PRs with bad test coverage
+ - Branch coverage on ruby 2.5+
 
 ```Ruby
 # Gemfile
@@ -11,7 +12,7 @@ gem 'single_cov', group: :test
 
 # spec/spec_helper.rb ... load before loading rails / minitest / libraries
 require 'single_cov'
-SingleCov.setup :rspec
+SingleCov.setup :rspec, branches: true
 
 # spec/foobar_spec.rb ... add covered! call to every test file
 require 'spec_helper'
@@ -36,7 +37,7 @@ lib/foobar.rb:23
 Call setup before loading minitest.
 
 ```Ruby
-SingleCov.setup :minitest
+SingleCov.setup :minitest, branches: true
 require 'minitest/autorun'
 ```
 
diff --git a/lib/single_cov.rb b/lib/single_cov.rb
index 0f60d3b..02a54e7 100644
--- a/lib/single_cov.rb
+++ b/lib/single_cov.rb
@@ -18,9 +18,17 @@ def covered!(file: nil, uncovered: 0)
     end
 
     def all_covered?(result)
+      result = result[:lines] || result
+
       errors = COVERAGES.map do |file, expected_uncovered|
         if coverage = result["#{root}/#{file}"]
-          uncovered_lines = coverage.each_with_index.map { |c, i| "#{file}:#{i+1}" if c == 0 }.compact
+          lines = (coverage.is_a?(Hash) ? coverage.fetch(:lines) : coverage)
+          uncovered_lines = line_coverage(file, lines)
+
+          if branches = (coverage.is_a?(Hash) && coverage[:branches])
+            uncovered_lines += branch_coverage(file, branches)
+          end
+
           next if uncovered_lines.size == expected_uncovered
           warn_about_bad_coverage(file, expected_uncovered, uncovered_lines)
         else
@@ -58,10 +66,16 @@ def assert_tested(files: glob('{app,lib}/**/*.rb'), tests: default_tests, untest
       end
     end
 
-    def setup(framework, root: nil)
+    def setup(framework, root: nil, branches: false)
       if defined?(SimpleCov)
         raise "Load SimpleCov after SingleCov"
       end
+      if branches && RUBY_VERSION < "2.5.0"
+        warn "Branch coverage needs ruby 2.5.0"
+        @branches = false
+      else
+        @branches = branches
+      end
 
       @root = root if root
 
@@ -89,6 +103,16 @@ def disable
 
     private
 
+    def line_coverage(file, coverage)
+      coverage.each_with_index.map { |c, i| "#{file}:#{i + 1}" if c == 0 }.compact
+    end
+
+    def branch_coverage(file, coverage)
+      coverage.each_value.flat_map do |branch_part|
+        branch_part.select { |_k, v| v == 0 }.map { |k, _| "#{file}:#{k[2]} branch #{k[2]}:#{k[3]+1}-#{k[4]}:#{k[5]+1}" }
+      end
+    end
+
     def default_tests
       glob("{test,spec}/**/*_{test,spec}.rb")
     end
@@ -110,7 +134,11 @@ def coverage_results
     # SimpleCov might start coverage again, but that does not hurt ...
     def start_coverage_recording
       require 'coverage'
-      Coverage.start
+      if @branches
+        Coverage.start(lines: true, branches: true)
+      else
+        Coverage.start
+      end
     end
 
     # not running rake or a whole folder
diff --git a/specs/single_cov_spec.rb b/specs/single_cov_spec.rb
index de5f669..a230892 100644
--- a/specs/single_cov_spec.rb
+++ b/specs/single_cov_spec.rb
@@ -3,6 +3,15 @@
 SingleCov.instance_variable_set(:@root, File.expand_path("../fixtures/minitest", __FILE__))
 
 describe SingleCov do
+  def self.it_does_not_complain_when_everything_is_covered
+    it "does not complain when everything is covered" do
+      result = sh "ruby test/a_test.rb"
+      assert_tests_finished_normally(result)
+      expect(result).to_not include "uncovered"
+    end
+  end
+
+
   it "has a VERSION" do
     expect(SingleCov::VERSION).to match(/^[\.\da-z]+$/)
   end
@@ -12,11 +21,7 @@
 
     around { |test| Dir.chdir("specs/fixtures/minitest", &test) }
 
-    it "does not complain when everything is covered" do
-      result = sh "ruby test/a_test.rb"
-      assert_tests_finished_normally(result)
-      expect(result).to_not include "uncovered"
-    end
+    it_does_not_complain_when_everything_is_covered
 
     it "is silent" do
       result = sh "ruby test/a_test.rb"
@@ -177,6 +182,26 @@
         end
       end
     end
+
+    describe "branch coverage" do
+      around { |t| change_file("test/a_test.rb", "root: root", "root: root, branches: true", &t) }
+
+      it_does_not_complain_when_everything_is_covered
+
+      describe "with branches" do
+        around { |t| change_file("lib/a.rb", "1", "2.times { |i| rand if i == 0 }", &t) }
+
+        it_does_not_complain_when_everything_is_covered
+
+        it "complains when coverage is missing" do
+          change_file("lib/a.rb", "i == 0", "i != i") do
+            result = sh "ruby test/a_test.rb", fail: true
+            expect(result).to include ".lib/a.rb new uncovered lines introduced (1 current vs 0 configured)"
+            expect(result).to include "lib/a.rb:3 branch 3:19-3:23"
+          end
+        end
+      end
+    end if RUBY_VERSION >= "2.5.0"
   end
 
   describe "rspec" do