From: Yusuke Endoh <mame@...>
Date: 2011-05-29T13:51:04+09:00
Subject: [ruby-core:36541] [Ruby 1.9 - Feature #4796][Assigned] Coverage should be restartable


Issue #4796 has been updated by Yusuke Endoh.

Category set to lib
Status changed from Open to Assigned
Assignee set to Yusuke Endoh
Target version set to 1.9.3

Hello.

As a maintainer of ext/coverage, I like to approve this feature unless
there is objection.  But I'd like to confirm some points.


2011/5/29 Xavier Shay <xavier-list@rhnh.net>:
> 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.

First of all, it is difficult to track files loaded before `start' is
first called.  This is because the VM compiler inserts instructions to
measure coverage after `start' is first called.  Since the mechanism
have considerable overhead, it cannot be enabled by default.

You are talking about second (or later) calls to Coverage.start, right?


>  Specifically, I am trying to collate coverage reports from workers in multiple processes.

I cannot understand why the feature is needed for this use case.
Could you elaborate this?


> Also I want to associate coverages with specific tests (this test executed this code, etc...). This is very difficult without being able to restart.

I can understand this.


Here is a patch.

diff --git a/ext/coverage/coverage.c b/ext/coverage/coverage.c
index 29ac709..3a26aaa 100644
--- a/ext/coverage/coverage.c
+++ b/ext/coverage/coverage.c
@@ -11,6 +11,8 @@
 #include "ruby.h"
 #include "vm_core.h"
 
+static VALUE rb_coverages = Qundef;
+
 /*
  * call-seq:
  *    Coverage.start  => nil
@@ -21,19 +23,25 @@ static VALUE
 rb_coverage_start(VALUE klass)
 {
     if (!RTEST(rb_get_coverages())) {
-	VALUE coverages = rb_hash_new();
-	RBASIC(coverages)->klass = 0;
-	rb_set_coverages(coverages);
+	if (rb_coverages == Qundef) {
+	    rb_coverages = rb_hash_new();
+	    RBASIC(rb_coverages)->klass = 0;
+	}
+	rb_set_coverages(rb_coverages);
     }
     return Qnil;
 }
 
 static int
-coverage_result_i(st_data_t key, st_data_t val, st_data_t dummy)
+coverage_result_i(st_data_t key, st_data_t val, st_data_t h)
 {
+    VALUE path = (VALUE)key;
     VALUE coverage = (VALUE)val;
-    RBASIC(coverage)->klass = rb_cArray;
+    VALUE coverages = (VALUE)h;
+    coverage = rb_ary_dup(coverage);
+    rb_ary_clear((VALUE)val);
     rb_ary_freeze(coverage);
+    rb_hash_aset(coverages, path, coverage);
     return ST_CONTINUE;
 }
 
@@ -48,14 +56,14 @@ static VALUE
 rb_coverage_result(VALUE klass)
 {
     VALUE coverages = rb_get_coverages();
+    VALUE ncoverages = rb_hash_new();
     if (!RTEST(coverages)) {
 	rb_raise(rb_eRuntimeError, "coverage measurement is not enabled");
     }
-    RBASIC(coverages)->klass = rb_cHash;
-    st_foreach(RHASH_TBL(coverages), coverage_result_i, 0);
-    rb_hash_freeze(coverages);
+    st_foreach(RHASH_TBL(coverages), coverage_result_i, ncoverages);
+    rb_hash_freeze(ncoverages);
     rb_reset_coverages();
-    return coverages;
+    return ncoverages;
 }
 
 /* Coverage provides coverage measurement feature for Ruby.

-- 
Yusuke Endoh <mame@tsg.ne.jp>
----------------------------------------
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.



-- 
http://redmine.ruby-lang.org