Replace colon with hyphen in plot filenames

Windows does not allow colons in filenames. Rather than have
different behavior on different platforms, we unconditionally
replace colons with hyphens when generating the plot filename.
This is the only place that we modify the nodeid.

Fixes #17.

pytest_plt/plugin.py

@@ -96,8 +96,9 @@ def dirname(self, _dirname):
 
     def get_filename(self, ext=""):
         # Flatten filestructure (replace folders with dots in filename).
-        # The nodeid should only contain /, but to be safe we also replace \\
-        filename = self.nodeid.replace("/", ".").replace("\\", ".")
+        # The nodeid should only contain /, but to be safe we also replace \\.
+        # We also replace : with - because Windows does not allow colons in filenames.
+        filename = self.nodeid.replace("/", ".").replace("\\", ".").replace(":", "-")
 
         # Drop parts of filename matching the given regexs
         for pattern in self.filename_drop:

pytest_plt/tests/test_pytest.py

@@ -48,7 +48,7 @@ def assert_all_passed(result):
     """
     outcomes = result.parseoutcomes()
     for outcome in outcomes:
-        if outcome not in ("passed", "seconds"):
+        if outcome not in ("passed", "seconds", "warnings"):
             assert outcomes[outcome] == 0
     return outcomes.get("passed", 0)
 
@@ -138,7 +138,7 @@ def test_filename_drop_prefix(testdir, prefix):
         for prefix_part, test_part in zip(prefix_parts, test_parts):
             assert prefix_part == test_part
 
-        plot_name = ".".join(test_parts[len(prefix_parts) :])
+        plot_name = ".".join(test_parts[len(prefix_parts) :]).replace(":", "-")
         assert plot in ["plots/%s.%s" % (plot_name, ext) for ext in ("pdf", "png")]
         assert os.path.exists(plot)
 
@@ -156,7 +156,7 @@ def test_filename_drop_within(testdir):
                 "plt_filename_drop =",
                 r"    package\.",
                 # Matches the `test_` of the function name only
-                r"    (?<=::)test_",
+                r"    (?<=--)test_",
             ]
         )
     )
@@ -170,8 +170,8 @@ def test_filename_drop_within(testdir):
     assert 0 < len(saved) <= n_passed
     for _, plot in saved:
         assert plot.startswith("plots/tests.test_")
-        colon_ix = plot.index("::")
-        assert not plot[colon_ix:].startswith("::test_")
+        colon_ix = plot.index("--")
+        assert not plot[colon_ix:].startswith("--test_")
 
 
 def test_plots_dir(testdir):