Improve rendering of collections in metadata (#132)

Render metadata collection values as comma seperated strings.

pytest_html/plugin.py

@@ -440,6 +440,8 @@ class HTMLReport(object):
             value = metadata[key]
             if isinstance(value, basestring) and value.startswith('http'):
                 value = html.a(value, href=value, target='_blank')
+            elif isinstance(value, (list, tuple, set)):
+                value = ', '.join((str(i) for i in value))
             rows.append(html.tr(html.td(key), html.td(value)))
 
         environment.append(html.table(rows, id='environment'))

testing/test_pytest_html.py

@@ -490,6 +490,24 @@ class TestHTML:
         assert 'Environment' in html
         assert len(re.findall(content, html)) == 1
 
+    def test_environment_list_value(self, testdir):
+        content = tuple(str(random.random()) for i in range(10))
+        content += tuple(random.random() for i in range(10))
+        expected_content = ', '.join((str(i) for i in content))
+        expected_html_re = '<td>content</td>\n\s+<td>{}</td>'.format(
+            expected_content
+        )
+        testdir.makeconftest("""
+            def pytest_configure(config):
+                for i in range(2):
+                    config._metadata['content'] = {0}
+        """.format(content))
+        testdir.makepyfile('def test_pass(): pass')
+        result, html = run(testdir)
+        assert result.ret == 0
+        assert 'Environment' in html
+        assert len(re.findall(expected_html_re, html)) == 1
+
     @pytest.mark.xfail(
         sys.version_info < (3, 2) and
         LooseVersion(pytest.__version__) >= LooseVersion('2.8.0'),