Truly ignore failures in skimage.

tools/tests/skimage_self_test.py

Index: tools/tests/skimage_self_test.py
diff --git a/tools/tests/skimage_self_test.py b/tools/tests/skimage_self_test.py
index 24164d4a5190b7bd397965127cedcab0e533ed3a..1f517132037a5277acb79c355f89b46db93c9d5c 100755
--- a/tools/tests/skimage_self_test.py
+++ b/tools/tests/skimage_self_test.py
@@ -39,6 +39,66 @@ def DieIfFilesMismatch(expected, actual):
             expected, actual)
         exit(1)
 
+def test_invalid_file(file_dir, skimage_binary):
+    """ Test the return value of skimage when an invalid file is decoded.
+        If there is no expectation file, or the file expects a particular
+        result, skimage should return nonzero indicating failure.
+        If the file has no expectation, or ignore-failure is set to true,
+        skimage should return zero indicating success. """
+    invalid_file = os.path.join(file_dir, "skimage", "input", "bad-images",
+                                "invalid.png")
+    # No expectations file:
+    args = [skimage_binary, "--readPath", invalid_file]
+    result = subprocess.call(args)
+    if 0 == result:
+      print "\"%s\" should have reported failure!" % " ".join(args)

[epoger, 2013/10/15 15:31:03]

Personally, I would write it this way to avoid the backslashes:

print "'%s' should have reported failure!" % " ".join(args)

I will note that, in the long term, we should move toward following
http://google-styleguide.googlecode.com/svn/trunk/pyguide.html , which calls for
single-quoted strings in Python.

print '"%s" should have reported failure!' % ' '.join(args)

[scroggo, 2013/10/15 19:50:59]

Done.
Maybe I'm looking in the wrong place, but inside
http://google-styleguide.googlecode.com/svn/trunk/pyguide.html?showone=String...
, it appears that the preference is to be consistent (which this file is not...)
rather than choosing one over the other.

[epoger, 2013/10/15 20:20:55]

Right.  I think consistency within the file is more important.  I just mentioned
this for future reference.

+      exit(1)
+
+    # Directory holding all expectations files
+    expectations_dir = os.path.join(file_dir, "skimage", "input", "bad-images")
+
+    # Expectations file expecting a valid decode:
+    incorrect_expectations = os.path.join(expectations_dir,
+                                          "incorrect-results.json")
+    args = [skimage_binary, "--readPath", invalid_file,
+            "--readExpectationsPath", incorrect_expectations]
+    result = subprocess.call(args)
+    if 0 == result:
+      print "\"%s\" should have reported failure!" % " ".join(args)
+      exit(1)
+
+    # Empty expectations:
+    empty_expectations = os.path.join(expectations_dir, "empty-results.json")
+    subprocess.check_call([skimage_binary, "--readPath", invalid_file,
+                           "--readExpectationsPath", empty_expectations])
+
+    # Ignore failure:
+    ignore_expectations = os.path.join(expectations_dir, "ignore-results.json")
+    subprocess.check_call([skimage_binary, "--readPath", invalid_file,
+                           "--readExpectationsPath", ignore_expectations])
+
+def test_incorrect_expectations(file_dir, skimage_binary):
+    """ Test that comparing to incorrect expectations fails, unless
+        ignore-failures is set to true. """
+    valid_file = os.path.join(file_dir, "skimage", "input",
+                                    "images-with-known-hashes",
+                                    "1209453360120438698.png")
+    expectations_dir = os.path.join(file_dir, "skimage", "input",
+                                    "images-with-known-hashes")
+
+    incorrect_results = os.path.join(expectations_dir,
+                                     "incorrect-results.json")
+    args = [skimage_binary, "--readPath", valid_file, "--readExpectationsPath",
+            incorrect_results]
+    result = subprocess.call(args)
+    if 0 == result:
+      print "\"%s\" should have reported failure!" % " ".join(args)
+      exit(1)
+
+    ignore_results = os.path.join(expectations_dir, "ignore-failures.json")
+    subprocess.check_call([skimage_binary, "--readPath", valid_file,
+                           "--readExpectationsPath", ignore_results])
+
 def main():
     # Use the directory of this file as the out directory
     file_dir = os.path.abspath(os.path.dirname(__file__))
@@ -68,8 +128,8 @@ def main():
     subprocess.check_call([skimage_binary, "--readPath", images_dir,
                            "--readExpectationsPath", expectations_path])
 
-    # TODO(scroggo): Add a test that compares expectations and image files that
-    # are known to NOT match, and make sure it returns an error.
+    test_incorrect_expectations(file_dir=file_dir,
+                                skimage_binary=skimage_binary)
 
     # Generate an expectations file from an empty directory.
     empty_dir = tempfile.mkdtemp()
@@ -91,6 +151,8 @@ def main():
                                        "nonexistent-dir", "expectations.json")
     DieIfFilesMismatch(expected=golden_expectations, actual=expectations_path)
 
+    test_invalid_file(file_dir=file_dir, skimage_binary=skimage_binary)
+
     # Done with all tests.
     print "Self tests succeeded!"