When reporting, don't fall over if there's no data to report on. Fixes issue #37.

3 files changed, 54 insertions, 14 deletions

diff --git a/test/coveragetest.py b/test/coveragetest.py
index dffffb29..3c22a0cf 100644
--- a/test/coveragetest.py
+++ b/test/coveragetest.py
@@ -1,6 +1,6 @@
 """Base test case class for coverage testing."""
 
-import difflib, imp, os, random, re, shutil, sys, tempfile, textwrap, unittest
+import difflib, imp, os, random, re, shlex, shutil, sys, tempfile, textwrap, unittest
 
 import coverage
 from coverage.backward import set, sorted, StringIO # pylint: disable-msg=W0622
@@ -20,6 +20,9 @@ class Tee(object):
             f.write(data)
 
 
+# Status returns for the command line.
+OK, ERR = 0, 1
+
 class CoverageTest(unittest.TestCase):
     """A base class for Coverage test cases."""
 
@@ -253,8 +256,30 @@ class CoverageTest(unittest.TestCase):
         fname = os.path.join(*fparts)
         return os.path.normcase(os.path.abspath(os.path.realpath(fname)))
     
+    def command_line(self, args, ret=OK):
+        """Run `args` through the command line.
+        
+        Use this when you want to run the full coverage machinery, but in the
+        current process.  Exceptions may be thrown from deep in the code.
+        Asserts that `ret` is returned by `CoverageScript.command_line`.
+        
+        Compare with `run_command`.
+        
+        Returns None.
+        
+        """
+        ret_actual = coverage.CoverageScript().command_line(shlex.split(args))
+        self.assertEqual(ret_actual, ret)
+        
     def run_command(self, cmd):
-        """ Run the command-line `cmd`, print its output.
+        """ Run the command-line `cmd` in a subprocess, and print its output.
+        
+        Use this when you need to test the process behavior of coverage.
+        
+        Compare with `command_line`.
+        
+        Returns the process' stdout text.
+        
         """
         # Add our test modules directory to PYTHONPATH.  I'm sure there's too
         # much path munging here, but...
diff --git a/test/test_cmdline.py b/test/test_cmdline.py
index 21639cdb..20c9c5d4 100644
--- a/test/test_cmdline.py
+++ b/test/test_cmdline.py
@@ -5,11 +5,9 @@ import mock
 import coverage
 
 sys.path.insert(0, os.path.split(__file__)[0]) # Force relative import for Py3k
-from coveragetest import CoverageTest
+from coveragetest import CoverageTest, OK, ERR
 
 
-OK, ERR = 0, 1
-
 class CmdLineTest(CoverageTest):
     """Tests of execution paths through the command line interpreter."""
     
@@ -19,15 +17,6 @@ class CmdLineTest(CoverageTest):
             .coverage(cover_pylib=None, data_suffix=False, timid=None, branch=None)
             .load()\n"""
 
-    def command_line(self, args, ret=OK):
-        """Run `args` through the command line.
-        
-        Checks that `ret` is returned.
-        
-        """
-        ret_actual = coverage.CoverageScript().command_line(shlex.split(args))
-        self.assertEqual(ret_actual, ret)
-        
     def model_object(self):
         """Return a Mock suitable for use in CoverageScript."""
         mk = mock.Mock()
diff --git a/test/test_coverage.py b/test/test_coverage.py
index 6544cddd..10cadfef 100644
--- a/test/test_coverage.py
+++ b/test/test_coverage.py
@@ -7,6 +7,8 @@ import os, sys, unittest
 import coverage
 coverage.use_cache(0)
 
+from coverage.misc import CoverageException
+
 sys.path.insert(0, os.path.split(__file__)[0]) # Force relative import for Py3k
 from coveragetest import CoverageTest
 
@@ -1674,6 +1676,30 @@ class ProcessTest(CoverageTest):
         self.assert_matches(out, "No file to run: .*xyzzy.py")
         self.assert_("Traceback" not in out)
 
+    def test_no_data_to_report_on_annotate(self):
+        # Reporting with no data produces a nice message and no output dir.
+        self.assert_raises_msg(
+            CoverageException, "No data to report.",
+            self.command_line, "annotate -d ann"
+            )
+        self.assertFalse(os.path.exists("ann"))
+
+    def test_no_data_to_report_on_html(self):
+        # Reporting with no data produces a nice message and no output dir.
+        self.assert_raises_msg(
+            CoverageException, "No data to report.",
+            self.command_line, "html -d htmlcov"
+            )
+        self.assertFalse(os.path.exists("htmlcov"))
+
+    def test_no_data_to_report_on_xml(self):
+        # Reporting with no data produces a nice message.
+        self.assert_raises_msg(
+            CoverageException, "No data to report.",
+            self.command_line, "xml"
+            )
+        # Currently, this leaves an empty coverage.xml file... :(
+
 
 if __name__ == '__main__':
     print("Testing under Python version: %s" % sys.version)