add nbdime test

Author: kandersolar

setup.py

@@ -22,6 +22,7 @@
     },
     install_requires = [
         'pytest >= 2.8',
+        'pytest-mock',
         'jupyter_client',
         'nbformat',
         'ipykernel',

tests/test_nbdime_reporter.py

@@ -0,0 +1,32 @@
+
+from utils import build_nb, add_expected_plaintext_outputs
+
+import nbdime
+import nbformat
+import os
+
+
+def test_nbdime(testdir, mocker):
+
+    # Make a test notebook where output doesn't match input
+    nb = build_nb(["1+1", "1+1"], mark_run=True)
+    add_expected_plaintext_outputs(nb, ["2", "3"])
+    # Write notebook to test dir
+    filename = 'test_nbdime.ipynb'
+    nbformat.write(nb, os.path.join(str(testdir.tmpdir), filename))
+
+    # patch the run_server function so that it doesn't actually
+    # spawn a server and display the diff.  But the diff is still
+    # calculated.
+    mocker.patch('nbdime.webapp.nbdiffweb.run_server')
+    result = testdir.runpytest_inprocess('--nbval',
+                                         '--nbval-current-env',
+                                         '--nbdime',
+                                         filename)
+    # run_server() is only called if there is a discrepancy in the notebook.
+    # so it should have been called in this case:
+    nbdime.webapp.nbdiffweb.run_server.assert_called_once()
+
+    # note: this import must be AFTER the mocker.patch
+    from nbval.nbdime_reporter import EXIT_TESTSFAILED
+    assert result.ret == EXIT_TESTSFAILED