feat: add support for Python 3.10 match-case statements

2 files changed, 69 insertions, 0 deletions

diff --git a/tests/test_arcs.py b/tests/test_arcs.py
index 495a10f3..22446f6a 100644
--- a/tests/test_arcs.py
+++ b/tests/test_arcs.py
@@ -1198,6 +1198,57 @@ class YieldTest(CoverageTest):
         )
 
 
+@pytest.mark.skipif(not env.PYBEHAVIOR.match_case, reason="Match-case is new in 3.10")
+class MatchCaseTest(CoverageTest):
+    """Tests of match-case."""
+    def test_match_case_with_default(self):
+        self.check_coverage("""\
+            for command in ["huh", "go home", "go n"]:
+                match command.split():
+                    case ["go", direction] if direction in "nesw":
+                        match = f"go: {direction}"
+                    case ["go", _]:
+                        match = "no go"
+                    case _:
+                        match = "default"
+                print(match)
+            """,
+            arcz=".1 12 23 34 49 35 56 69 58 89 91 1.",
+        )
+        assert self.stdout() == "default\nno go\ngo: n\n"
+
+    def test_match_case_with_wildcard(self):
+        self.check_coverage("""\
+            for command in ["huh", "go home", "go n"]:
+                match command.split():
+                    case ["go", direction] if direction in "nesw":
+                        match = f"go: {direction}"
+                    case ["go", _]:
+                        match = "no go"
+                    case x:
+                        match = f"default: {x}"
+                print(match)
+            """,
+            arcz=".1 12 23 34 49 35 56 69 57 78 89 91 1.",
+        )
+        assert self.stdout() == "default: ['huh']\nno go\ngo: n\n"
+
+    def test_match_case_without_wildcard(self):
+        self.check_coverage("""\
+            match = None
+            for command in ["huh", "go home", "go n"]:
+                match command.split():
+                    case ["go", direction] if direction in "nesw":
+                        match = f"go: {direction}"
+                    case ["go", _]:
+                        match = "no go"
+                print(match)
+            """,
+            arcz=".1 12 23 34 45 58 46 78 67 68 82 2.",
+        )
+        assert self.stdout() == "None\nno go\ngo: n\n"
+
+
 class OptimizedIfTest(CoverageTest):
     """Tests of if statements being optimized away."""
 
diff --git a/tests/test_parser.py b/tests/test_parser.py
index 7fd87bba..1b4e8aca 100644
--- a/tests/test_parser.py
+++ b/tests/test_parser.py
@@ -394,6 +394,24 @@ class ParserMissingArcDescriptionTest(CoverageTest):
             """)
         assert parser.missing_arc_description(2, -3) == "line 3 didn't finish the lambda on line 3"
 
+    @pytest.mark.skipif(not env.PYBEHAVIOR.match_case, reason="Match-case is new in 3.10")
+    def test_match_case_with_default(self):
+        parser = self.parse_text("""\
+            for command in ["huh", "go home", "go n"]:
+                match command.split():
+                    case ["go", direction] if direction in "nesw":
+                        match = f"go: {direction}"
+                    case ["go", _]:
+                        match = "no go"
+                print(match)
+            """)
+        assert parser.missing_arc_description(3, 4) == (
+            "line 3 didn't jump to line 4, because the pattern on line 3 never matched"
+            )
+        assert parser.missing_arc_description(3, 5) == (
+            "line 3 didn't jump to line 5, because the pattern on line 3 always matched"
+            )
+
 
 class ParserFileTest(CoverageTest):
     """Tests for coverage.py's code parsing from files."""