feat: add support for Python 3.10 match-case statements

1 files changed, 21 insertions, 0 deletions

diff --git a/coverage/parser.py b/coverage/parser.py
index ff395dad..abaa2e50 100644
--- a/coverage/parser.py
+++ b/coverage/parser.py
@@ -1018,6 +1018,27 @@ class AstArcAnalyzer:
         return exits
 
     @contract(returns='ArcStarts')
+    def _handle__Match(self, node):
+        start = self.line_for_node(node)
+        last_start = start
+        exits = set()
+        had_wildcard = False
+        for case in node.cases:
+            # The wildcard case doesn't execute the pattern.
+            case_start = self.line_for_node(case.pattern)
+            if isinstance(case.pattern, ast.MatchAs):
+                had_wildcard = True
+                if case.pattern.name is None:
+                    case_start = self.line_for_node(case.body[0])
+            self.add_arc(last_start, case_start, "the pattern on line {lineno} always matched")
+            from_start = ArcStart(case_start, cause="the pattern on line {lineno} never matched")
+            exits |= self.add_body_arcs(case.body, from_start=from_start)
+            last_start = case_start
+        if not had_wildcard:
+            exits.add(from_start)
+        return exits
+
+    @contract(returns='ArcStarts')
     def _handle__NodeList(self, node):
         start = self.line_for_node(node)
         exits = self.add_body_arcs(node.body, from_start=ArcStart(start))