fix: colons in decorators shouldn't stop an exclusion

3 files changed, 30 insertions, 4 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 15c81aaf..0b6e2490 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -22,7 +22,8 @@ This list is detailed and covers changes in each pre-release version.
 Unreleased
 ----------
 
-Nothing yet.
+- Fix: A colon in a decorator expression would cause an exclusion to end too
+  early, preventing the exclusion of the decorated function. This is now fixed.
 
 
 .. _changes_612:
diff --git a/coverage/parser.py b/coverage/parser.py
index ec788c06..b47fd12e 100644
--- a/coverage/parser.py
+++ b/coverage/parser.py
@@ -67,7 +67,7 @@ class PythonParser:
         # The raw line numbers of excluded lines of code, as marked by pragmas.
         self.raw_excluded = set()
 
-        # The line numbers of class and function definitions.
+        # The line numbers of class definitions.
         self.raw_classdefs = set()
 
         # The line numbers of docstring lines.
@@ -120,6 +120,7 @@ class PythonParser:
         first_line = None
         empty = True
         first_on_line = True
+        nesting = 0
 
         tokgen = generate_tokens(self.text)
         for toktype, ttext, (slineno, _), (elineno, _), ltext in tokgen:
@@ -139,7 +140,7 @@ class PythonParser:
                     # lines with the 'class' keyword.
                     self.raw_classdefs.add(slineno)
             elif toktype == token.OP:
-                if ttext == ':':
+                if ttext == ':' and nesting == 0:
                     should_exclude = (elineno in self.raw_excluded) or excluding_decorators
                     if not excluding and should_exclude:
                         # Start excluding a suite.  We trigger off of the colon
@@ -155,6 +156,10 @@ class PythonParser:
                         excluding_decorators = True
                     if excluding_decorators:
                         self.raw_excluded.add(elineno)
+                elif ttext in "([{":
+                    nesting += 1
+                elif ttext in ")]}":
+                    nesting -= 1
             elif toktype == token.STRING and prev_toktype == token.INDENT:
                 # Strings that are first on an indented line are docstrings.
                 # (a trick from trace.py in the stdlib.) This works for
diff --git a/tests/test_parser.py b/tests/test_parser.py
index d5f43197..303f2b55 100644
--- a/tests/test_parser.py
+++ b/tests/test_parser.py
@@ -174,10 +174,30 @@ class PythonParserTest(CoverageTest):
             """)
         raw_statements = {3, 4, 5, 6, 8, 9, 10, 13, 15, 16, 17, 20, 22, 23, 25, 26}
         if env.PYBEHAVIOR.trace_decorated_def:
-            raw_statements.update([11, 19])
+            raw_statements.update({11, 19})
         assert parser.raw_statements == raw_statements
         assert parser.statements == {8}
 
+    def test_decorator_pragmas_with_colons(self):
+        # A colon in a decorator expression would confuse the parser,
+        # ending the exclusion of the decorated function.
+        parser = self.parse_source("""\
+            @decorate(X)        # nocover
+            @decorate("Hello"[2])
+            def f():
+                x = 4
+
+            @decorate(X)        # nocover
+            @decorate("Hello"[:7])
+            def g():
+                x = 9
+            """)
+        raw_statements = {1, 2, 4, 6, 7, 9}
+        if env.PYBEHAVIOR.trace_decorated_def:
+            raw_statements.update({3, 8})
+        assert parser.raw_statements == raw_statements
+        assert parser.statements == set()
+
     def test_class_decorator_pragmas(self):
         parser = self.parse_source("""\
             class Foo(object):