Make return codes consistent: 1 for no data and 2 for fail_under. Now…

… the `report` command will properly report `No data to report` if there's no data.

coverage/html.py

@@ -126,8 +126,7 @@ def report(self, morfs):
         self.index_file()
 
         self.make_local_static_report_files()
-
-        return self.totals.pc_covered
+        return self.totals.n_statements and self.totals.pc_covered
 
     def make_local_static_report_files(self):
         """Make local instances of static files for HTML report."""

coverage/summary.py

@@ -98,5 +98,6 @@ def report(self, morfs, outfile=None):
             if self.config.show_missing:
                 args += ("",)
             outfile.write(fmt_coverage % args)
-
+        if not total.n_files:
+            raise CoverageException("No data to report.")
         return total.n_statements and total.pc_covered

tests/test_process.py

@@ -703,17 +703,15 @@ def test_fail_under_in_config(self):
         st, _ = self.run_command_status("coverage report")
         self.assertEqual(st, 2)
 
-class FailUnderNoDataTest(CoverageTest):
-    def setUp(self):
-        super(FailUnderNoDataTest, self).setUp()
 
+class FailUnderNoFilesTest(CoverageTest):
+    def setUp(self):
+        super(FailUnderNoFilesTest, self).setUp()
         self.make_file(".coveragerc", "[report]\nfail_under = 99\n")
-        if os.path.exists('.coverage'):
-            os.remove('.coverage')
 
     def test_report(self):
         st, _ = self.run_command_status("coverage report")
-        self.assertEqual(st, 2)
+        self.assertEqual(st, 1)
 
     def test_xml(self):
         st, _ = self.run_command_status("coverage xml")
@@ -724,6 +722,28 @@ def test_html(self):
         self.assertEqual(st, 1)
 
 
+class FailUnderEmptyFilesTest(CoverageTest):
+    def setUp(self):
+        super(FailUnderEmptyFilesTest, self).setUp()
+
+        self.make_file(".coveragerc", "[report]\nfail_under = 99\n")
+        self.make_file("empty.py", "")
+        st, _ = self.run_command_status("coverage run empty.py")
+        self.assertEqual(st, 0)
+
+    def test_report(self):
+        st, _ = self.run_command_status("coverage report")
+        self.assertEqual(st, 2)
+
+    def test_xml(self):
+        st, _ = self.run_command_status("coverage xml")
+        self.assertEqual(st, 2)
+
+    def test_html(self):
+        st, _ = self.run_command_status("coverage html")
+        self.assertEqual(st, 2)
+
+
 def possible_pth_dirs():
     """Produce a sequence of directories for trying to write .pth files."""
     # First look through sys.path, and we find a .pth file, then it's a good