Debugging plugin wrappers

5 files changed, 169 insertions, 18 deletions

diff --git a/coverage/control.py b/coverage/control.py
index 3cae1d36..b982c792 100644
--- a/coverage/control.py
+++ b/coverage/control.py
@@ -202,7 +202,7 @@ class Coverage(object):
         self.debug = DebugControl(self.config.debug, self._debug_file)
 
         # Load plugins
-        self.plugins = Plugins.load_plugins(self.config.plugins, self.config)
+        self.plugins = Plugins.load_plugins(self.config.plugins, self.config, self.debug)
 
         self.file_tracing_plugins = []
         for plugin in self.plugins:
diff --git a/coverage/plugin.py b/coverage/plugin.py
index 6648d7a6..3fbb43aa 100644
--- a/coverage/plugin.py
+++ b/coverage/plugin.py
@@ -3,8 +3,10 @@
 import os
 import re
 
+from coverage import files
 from coverage.misc import _needs_to_implement
 
+
 # TODO: document that the plugin objects may be decorated with attributes with
 # named "_coverage_*".
 
@@ -25,7 +27,7 @@ class CoveragePlugin(object):
 
     """
 
-    def __init__(self, options):
+    def __init__(self, options=None):
         """
         When the plugin is constructed, it will be passed a dictionary of
         plugin-specific options read from the .coveragerc configuration file.
@@ -36,7 +38,7 @@ class CoveragePlugin(object):
                 .coveragerc configuration file.
 
         """
-        self.options = options
+        self.options = options or {}
 
     def file_tracer(self, filename):        # pylint: disable=unused-argument
         """Return a FileTracer object for a file.
@@ -175,6 +177,9 @@ class FileReporter(object):
             " filename={self.filename!r}>".format(self=self)
         )
 
+    def relative_filename(self):
+        return files.relative_filename(self.filename)
+
     # Annoying comparison operators. Py3k wants __lt__ etc, and Py2k needs all
     # of them defined.
 
@@ -247,6 +252,8 @@ class FileReporter(object):
 
         For example, the file a/b/c.py will return 'a_b_c_py'
 
+        You should not need to override this method.
+
         """
-        name = os.path.splitdrive(self.name)[1]
+        name = os.path.splitdrive(self.relative_filename())[1]
         return re.sub(r"[\\/.:]", "_", name)
diff --git a/coverage/plugin_support.py b/coverage/plugin_support.py
index 9ab79544..8bdc7213 100644
--- a/coverage/plugin_support.py
+++ b/coverage/plugin_support.py
@@ -3,6 +3,7 @@
 import sys
 
 from coverage.misc import CoverageException
+from coverage.plugin import CoveragePlugin, FileTracer, FileReporter
 
 
 class Plugins(object):
@@ -13,7 +14,7 @@ class Plugins(object):
         self.names = {}
 
     @classmethod
-    def load_plugins(cls, modules, config):
+    def load_plugins(cls, modules, config, debug=None):
         """Load plugins from `modules`.
 
         Returns a list of loaded and configured plugins.
@@ -31,6 +32,10 @@ class Plugins(object):
 
             options = config.get_plugin_options(module)
             plugin = plugin_class(options)
+            if debug and debug.should('plugin'):
+                debug.write("Loaded plugin %r: %r" % (module, plugin))
+                labelled = LabelledDebug("plugin %r" % (module,), debug)
+                plugin = DebugPluginWrapper(plugin, labelled)
             plugin._coverage_plugin_name = module
             plugin._coverage_enabled = True
             plugins.order.append(plugin)
@@ -49,3 +54,139 @@ class Plugins(object):
     def get(self, plugin_name):
         """Return a plugin by name."""
         return self.names[plugin_name]
+
+
+class LabelledDebug(object):
+    """A Debug writer, but with labels for prepending to the messages."""
+
+    def __init__(self, label, debug, prev_labels=()):
+        self.labels = list(prev_labels) + [label]
+        self.debug = debug
+
+    def add_label(self, label):
+        """Add a label to the writer, and return a new `LabelledDebug`."""
+        return LabelledDebug(label, self.debug, self.labels)
+
+    def write(self, message):
+        """Write `message`, but with the labels prepended."""
+        self.debug.write("%s: %s" % (", ".join(self.labels), message))
+
+
+class DebugPluginWrapper(CoveragePlugin):
+    """Wrap a plugin, and use debug to report on what it's doing."""
+
+    def __init__(self, plugin, debug):
+        super(DebugPluginWrapper, self).__init__()
+        self.plugin = plugin
+        self.debug = debug
+
+    def file_tracer(self, filename):
+        tracer = self.plugin.file_tracer(filename)
+        self.debug.write("file_tracer(%r) --> %r" % (filename, tracer))
+        if tracer:
+            debug = self.debug.add_label("file %r" % (filename,))
+            tracer = DebugFileTracerWrapper(tracer, debug)
+        return tracer
+
+    def file_reporter(self, filename):
+        reporter = self.plugin.file_reporter(filename)
+        self.debug.write("file_reporter(%r) --> %r" % (filename, reporter))
+        if reporter:
+            debug = self.debug.add_label("file %r" % (filename,))
+            reporter = DebugFileReporterWrapper(filename, reporter, debug)
+        return reporter
+
+    def sys_info(self):
+        return self.plugin.sys_info()
+
+
+class DebugFileTracerWrapper(FileTracer):
+    """A debugging `FileTracer`."""
+
+    def __init__(self, tracer, debug):
+        self.tracer = tracer
+        self.debug = debug
+
+    def source_filename(self):
+        sfilename = self.tracer.source_filename()
+        self.debug.write("source_filename() --> %r" % (sfilename,))
+        return sfilename
+
+    def has_dynamic_source_filename(self):
+        has = self.tracer.has_dynamic_source_filename()
+        self.debug.write("has_dynamic_source_filename() --> %r" % (has,))
+        return has
+
+    def dynamic_source_filename(self, filename, frame):
+        dyn = self.tracer.dynamic_source_filename(filename, frame)
+        self.debug.write("dynamic_source_filename(%r, frame) --> %r" % (filename, dyn))
+        return dyn
+
+    def line_number_range(self, frame):
+        pair = self.tracer.line_number_range(frame)
+        self.debug.write("line_number_range(frame) --> %r" % (pair,))
+        return pair
+
+
+class DebugFileReporterWrapper(FileReporter):
+    """A debugging `FileReporter`."""
+
+    def __init__(self, filename, reporter, debug):
+        super(DebugFileReporterWrapper, self).__init__(filename)
+        self.reporter = reporter
+        self.debug = debug
+
+    def relative_filename(self):
+        ret = self.reporter.relative_filename()
+        self.debug.write("relative_filename() --> %r" % (ret,))
+        return ret
+
+    def statements(self):
+        ret = self.reporter.statements()
+        self.debug.write("statements() --> %r" % (ret,))
+        return ret
+
+    def excluded_statements(self):
+        ret = self.reporter.excluded_statements()
+        self.debug.write("excluded_statements() --> %r" % (ret,))
+        return ret
+
+    def translate_lines(self, lines):
+        ret = self.reporter.translate_lines(lines)
+        self.debug.write("translate_lines(%r) --> %r" % (lines, ret))
+        return ret
+
+    def translate_arcs(self, arcs):
+        ret = self.reporter.translate_arcs(arcs)
+        self.debug.write("translate_arcs(%r) --> %r" % (arcs, ret))
+        return ret
+
+    def no_branch_lines(self):
+        ret = self.reporter.no_branch_lines()
+        self.debug.write("no_branch_lines() --> %r" % (ret,))
+        return ret
+
+    def exit_counts(self):
+        ret = self.reporter.exit_counts()
+        self.debug.write("exit_counts() --> %r" % (ret,))
+        return ret
+
+    def arcs(self):
+        ret = self.reporter.arcs()
+        self.debug.write("arcs() --> %r" % (ret,))
+        return ret
+
+    def source(self):
+        ret = self.reporter.source()
+        self.debug.write("source() --> %d chars" % (len(ret),))
+        return ret
+
+    def source_token_lines(self):
+        ret = list(self.reporter.source_token_lines())
+        self.debug.write("source_token_lines() --> %d tokens" % (len(ret),))
+        return ret
+
+    def should_be_python(self):
+        ret = self.reporter.should_be_python()
+        self.debug.write("should_be_python() --> %r" % (ret,))
+        return ret
diff --git a/coverage/python.py b/coverage/python.py
index 8dc163df..b1667f6d 100644
--- a/coverage/python.py
+++ b/coverage/python.py
@@ -103,13 +103,16 @@ class PythonFileReporter(FileReporter):
             name = name.replace(".", os.sep) + ".py"
         else:
             name = files.relative_filename(filename)
-        self.name = name
+        self.relname = name
 
         self._source = None
         self._parser = None
         self._statements = None
         self._excluded = None
 
+    def relative_filename(self):
+        return self.relname
+
     @property
     def parser(self):
         if self._parser is None:
diff --git a/tests/test_filereporter.py b/tests/test_filereporter.py
index 9db4c0c3..045081cf 100644
--- a/tests/test_filereporter.py
+++ b/tests/test_filereporter.py
@@ -32,9 +32,9 @@ class FileReporterTest(CoverageTest):
         acu = PythonFileReporter("aa/afile.py")
         bcu = PythonFileReporter("aa/bb/bfile.py")
         ccu = PythonFileReporter("aa/bb/cc/cfile.py")
-        self.assertEqual(acu.name, "aa/afile.py")
-        self.assertEqual(bcu.name, "aa/bb/bfile.py")
-        self.assertEqual(ccu.name, "aa/bb/cc/cfile.py")
+        self.assertEqual(acu.relative_filename(), "aa/afile.py")
+        self.assertEqual(bcu.relative_filename(), "aa/bb/bfile.py")
+        self.assertEqual(ccu.relative_filename(), "aa/bb/cc/cfile.py")
         self.assertEqual(acu.flat_rootname(), "aa_afile_py")
         self.assertEqual(bcu.flat_rootname(), "aa_bb_bfile_py")
         self.assertEqual(ccu.flat_rootname(), "aa_bb_cc_cfile_py")
@@ -46,9 +46,9 @@ class FileReporterTest(CoverageTest):
         acu = PythonFileReporter("aa/afile.odd.py")
         bcu = PythonFileReporter("aa/bb/bfile.odd.py")
         b2cu = PythonFileReporter("aa/bb.odd/bfile.py")
-        self.assertEqual(acu.name, "aa/afile.odd.py")
-        self.assertEqual(bcu.name, "aa/bb/bfile.odd.py")
-        self.assertEqual(b2cu.name, "aa/bb.odd/bfile.py")
+        self.assertEqual(acu.relative_filename(), "aa/afile.odd.py")
+        self.assertEqual(bcu.relative_filename(), "aa/bb/bfile.odd.py")
+        self.assertEqual(b2cu.relative_filename(), "aa/bb.odd/bfile.py")
         self.assertEqual(acu.flat_rootname(), "aa_afile_odd_py")
         self.assertEqual(bcu.flat_rootname(), "aa_bb_bfile_odd_py")
         self.assertEqual(b2cu.flat_rootname(), "aa_bb_odd_bfile_py")
@@ -64,9 +64,9 @@ class FileReporterTest(CoverageTest):
         acu = PythonFileReporter(aa)
         bcu = PythonFileReporter(aa.bb)
         ccu = PythonFileReporter(aa.bb.cc)
-        self.assertEqual(acu.name, native("aa.py"))
-        self.assertEqual(bcu.name, native("aa/bb.py"))
-        self.assertEqual(ccu.name, native("aa/bb/cc.py"))
+        self.assertEqual(acu.relative_filename(), native("aa.py"))
+        self.assertEqual(bcu.relative_filename(), native("aa/bb.py"))
+        self.assertEqual(ccu.relative_filename(), native("aa/bb/cc.py"))
         self.assertEqual(acu.flat_rootname(), "aa_py")
         self.assertEqual(bcu.flat_rootname(), "aa_bb_py")
         self.assertEqual(ccu.flat_rootname(), "aa_bb_cc_py")
@@ -82,9 +82,9 @@ class FileReporterTest(CoverageTest):
         acu = PythonFileReporter(aa.afile)
         bcu = PythonFileReporter(aa.bb.bfile)
         ccu = PythonFileReporter(aa.bb.cc.cfile)
-        self.assertEqual(acu.name, native("aa/afile.py"))
-        self.assertEqual(bcu.name, native("aa/bb/bfile.py"))
-        self.assertEqual(ccu.name, native("aa/bb/cc/cfile.py"))
+        self.assertEqual(acu.relative_filename(), native("aa/afile.py"))
+        self.assertEqual(bcu.relative_filename(), native("aa/bb/bfile.py"))
+        self.assertEqual(ccu.relative_filename(), native("aa/bb/cc/cfile.py"))
         self.assertEqual(acu.flat_rootname(), "aa_afile_py")
         self.assertEqual(bcu.flat_rootname(), "aa_bb_bfile_py")
         self.assertEqual(ccu.flat_rootname(), "aa_bb_cc_cfile_py")