Make HTML tests impervious to clock issues arising from timestamps

1 files changed, 46 insertions, 28 deletions

diff --git a/tests/test_html.py b/tests/test_html.py
index 75169ba..2de6b68 100644
--- a/tests/test_html.py
+++ b/tests/test_html.py
@@ -54,6 +54,23 @@ class HtmlTestHelpers(CoverageTest):
         with open(filename) as f:
             return f.read()
 
+    def get_html_index_content(self, scrub_time_stamp=True):
+        """Return the content of index.html.
+
+        If `scrub_time_stamp` is true, then replace the timestamp with a
+        placeholder so that clocks don't matter.
+
+        """
+        with open("htmlcov/index.html") as f:
+            index = f.read()
+        if scrub_time_stamp:
+            index = re.sub(
+                r"created at \d{4}-\d{2}-\d{2} \d{2}:\d{2}",
+                r"created at YYYY-MM-DD HH:MM",
+                index,
+            )
+        return index
+
 
 class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
     """Tests of the HTML delta speed-ups."""
@@ -87,8 +104,7 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         # In this case, helper1 changes because its source is different.
         self.create_initial_files()
         self.run_coverage()
-        with open("htmlcov/index.html") as f:
-            index1 = f.read()
+        index1 = self.get_html_index_content()
         self.remove_html_files()
 
         # Now change a file and do it again
@@ -105,8 +121,7 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         self.assert_exists("htmlcov/helper1_py.html")
         self.assert_doesnt_exist("htmlcov/main_file_py.html")
         self.assert_doesnt_exist("htmlcov/helper2_py.html")
-        with open("htmlcov/index.html") as f:
-            index2 = f.read()
+        index2 = self.get_html_index_content()
         self.assertMultiLineEqual(index1, index2)
 
     def test_html_delta_from_coverage_change(self):
@@ -137,8 +152,7 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         # changed.
         self.create_initial_files()
         self.run_coverage(covargs=dict(omit=[]))
-        with open("htmlcov/index.html") as f:
-            index1 = f.read()
+        index1 = self.get_html_index_content()
         self.remove_html_files()
 
         self.run_coverage(covargs=dict(omit=['xyzzy*']))
@@ -148,8 +162,7 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         self.assert_exists("htmlcov/helper1_py.html")
         self.assert_exists("htmlcov/main_file_py.html")
         self.assert_exists("htmlcov/helper2_py.html")
-        with open("htmlcov/index.html") as f:
-            index2 = f.read()
+        index2 = self.get_html_index_content()
         self.assertMultiLineEqual(index1, index2)
 
     def test_html_delta_from_coverage_version_change(self):
@@ -158,8 +171,7 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         # changed.
         self.create_initial_files()
         self.run_coverage()
-        with open("htmlcov/index.html") as f:
-            index1 = f.read()
+        index1 = self.get_html_index_content()
         self.remove_html_files()
 
         # "Upgrade" coverage.py!
@@ -172,8 +184,7 @@ class HtmlDeltaTest(HtmlTestHelpers, CoverageTest):
         self.assert_exists("htmlcov/helper1_py.html")
         self.assert_exists("htmlcov/main_file_py.html")
         self.assert_exists("htmlcov/helper2_py.html")
-        with open("htmlcov/index.html") as f:
-            index2 = f.read()
+        index2 = self.get_html_index_content()
         fixed_index2 = index2.replace("XYZZY", self.real_coverage_version)
         self.assertMultiLineEqual(index1, fixed_index2)
 
@@ -184,8 +195,7 @@ class HtmlTitleTest(HtmlTestHelpers, CoverageTest):
     def test_default_title(self):
         self.create_initial_files()
         self.run_coverage()
-        with open("htmlcov/index.html") as f:
-            index = f.read()
+        index = self.get_html_index_content()
         self.assertIn("<title>Coverage report</title>", index)
         self.assertIn("<h1>Coverage report:", index)
 
@@ -193,8 +203,7 @@ class HtmlTitleTest(HtmlTestHelpers, CoverageTest):
         self.create_initial_files()
         self.make_file(".coveragerc", "[html]\ntitle = Metrics & stuff!\n")
         self.run_coverage()
-        with open("htmlcov/index.html") as f:
-            index = f.read()
+        index = self.get_html_index_content()
         self.assertIn("<title>Metrics &amp; stuff!</title>", index)
         self.assertIn("<h1>Metrics &amp; stuff!:", index)
 
@@ -204,8 +213,7 @@ class HtmlTitleTest(HtmlTestHelpers, CoverageTest):
             "[html]\ntitle = «ταБЬℓσ» numbers"
             )
         self.run_coverage()
-        with open("htmlcov/index.html") as f:
-            index = f.read()
+        index = self.get_html_index_content()
         self.assertIn(
             "<title>&#171;&#964;&#945;&#1041;&#1068;&#8467;&#963;&#187;"
             " numbers", index
@@ -219,8 +227,7 @@ class HtmlTitleTest(HtmlTestHelpers, CoverageTest):
         self.create_initial_files()
         self.make_file(".coveragerc", "[html]\ntitle = Good title\n")
         self.run_coverage(htmlargs=dict(title="«ταБЬℓσ» & stüff!"))
-        with open("htmlcov/index.html") as f:
-            index = f.read()
+        index = self.get_html_index_content()
         self.assertIn(
             "<title>&#171;&#964;&#945;&#1041;&#1068;&#8467;&#963;&#187;"
             " &amp; st&#252;ff!</title>", index
@@ -364,18 +371,29 @@ class HtmlTest(HtmlTestHelpers, CoverageTest):
         self.assert_exists("htmlcov/afile.html")
         self.assert_exists("htmlcov/afile_py.html")
 
-    def test_has_date_stamp_in_index(self):
+    def test_has_date_stamp_in_files(self):
         self.create_initial_files()
         self.run_coverage()
-        # Note: in theory this test could fail if the HTML files are created
-        # at 1:23:59.999 and this timestamp is grabbed at 1:24:00.000.
-        footer = "created at {time_stamp}".format(
-            time_stamp=datetime.datetime.now().strftime('%Y-%m-%d %H:%M')
-            )
+
         with open("htmlcov/index.html") as f:
-            self.assertIn(footer, f.read())
+            self.assert_correct_timestamp(f.read())
         with open("htmlcov/main_file_py.html") as f:
-            self.assertIn(footer, f.read())
+            self.assert_correct_timestamp(f.read())
+
+    def assert_correct_timestamp(self, html):
+        """Extract the timestamp from `html`, and assert it is recent."""
+        timestamp_pat = r"created at (\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2})"
+        m = re.search(timestamp_pat, html)
+        self.assertTrue(m, "Didn't find a timestamp!")
+        timestamp = datetime.datetime(*map(int, m.groups()))
+        age = datetime.datetime.now() - timestamp
+        # The timestamp only records the minute, so the delta could be from
+        # 12:00 to 12:01:59, or two minutes.
+        self.assertLessEqual(
+            abs(age.total_seconds()),
+            120,
+            "Timestamp is wrong: {}".format(timestamp)
+        )
 
 
 class HtmlStaticFileTest(CoverageTest):