Issue #4796 has been updated by Xavier Shay.


I tried this patch and it works as expected. Here is a patch for the test case, slightly cleaned up:

diff --git a/test/coverage/test_coverage.rb b/test/coverage/test_coverage.rb
index ace49d3..56966b1 100644
--- a/test/coverage/test_coverage.rb
+++ b/test/coverage/test_coverage.rb
@@ -1,5 +1,6 @@
 require "test/unit"
 require "coverage"
+require "tmpdir"
 
 class TestCoverage < Test::Unit::TestCase
   def test_result_without_start
@@ -14,4 +15,29 @@ class TestCoverage < Test::Unit::TestCase
       assert_kind_of(Array, val)
     end
   end
+
+  def test_restarting_coverage
+    loaded_features = $".dup
+
+    Dir.mktmpdir {|tmp|
+      Dir.chdir(tmp) {
+        File.open("test.rb", "w") do |f|
+          f.puts <<-EOS
+            def coverage_test_method
+              :ok
+            end
+          EOS
+        end
+
+        Coverage.start
+        require tmp + '/test.rb'
+        Coverage.result
+        Coverage.start
+        coverage_test_method
+        assert_equal 1, Coverage.result.size
+      }
+    }
+  ensure
+    $".replace loaded_features
+  end
 end
----------------------------------------
Feature #4796: Coverage should be restartable
http://redmine.ruby-lang.org/issues/4796

Author: Xavier Shay
Status: Assigned
Priority: Normal
Assignee: Yusuke Endoh
Category: lib
Target version: 1.9.3


I would like a way to be able to make the following test past:

    require "test/unit"
    require "coverage"
    require 'tmpdir'

    class TestCoverage < Test::Unit::TestCase
      def test_restarting_coverage
        Dir.mktmpdir {|tmp|
          Dir.chdir(tmp) {
            File.open("test.rb", "w") do |f|
              f.puts <<-EOS
                def coverage_test_method
                  puts :ok
                end
              EOS
            end

            Coverage.start
            require tmp + '/test.rb'
            Coverage.result
            Coverage.start
            coverage_test_method
            assert_equal 1, Coverage.result.size
          }
        }
      end
    end

The problem is that `Coverage.start` doesn't track any files loaded before it is called. This is probably desired behaviour so that stdlib files are not tracked, but it limits the usefulness of Coverage. Specifically, I am trying to collate coverage reports from workers in multiple processes. Also I want to associate coverages with specific tests (this test executed this code, etc...). This is very difficult without being able to restart.

What would be involved in doing this? If you point me in the right direction I can perhaps have a go.



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