fix: didn't-ectomy. #1873

Author: nedbat

CHANGES.rst

@@ -23,7 +23,10 @@ upgrading your version of coverage.py.
 Unreleased
 ----------
 
-Nothing yet.
+- Fix: the missing branch message about not exiting a module had an extra
+  "didn't," as described in `issue 1873`_.  This is now fixed.
+
+.. _issue 1873: https://github.com/nedbat/coveragepy/issues/1873
 
 
 .. start-releases

coverage/parser.py

@@ -719,7 +719,7 @@ def _code_object__Module(self, node: ast.Module) -> None:
         if node.body:
             exits = self.process_body(node.body)
             for xit in exits:
-                self.add_arc(xit.lineno, -start, xit.cause, "didn't exit the module")
+                self.add_arc(xit.lineno, -start, xit.cause, "exit the module")
         else:
             # Empty module.
             self.add_arc(start, -start)

tests/test_arcs.py

@@ -323,6 +323,19 @@ def f(x):
         expected = "line 3 didn't jump to the function exit"
         assert self.get_missing_arc_description(cov, 3, -2) == expected
 
+    def test_leaving_module(self) -> None:
+        cov = self.check_coverage("""\
+            print(a := 1)
+            if a == 1:
+                print(3)
+            """,
+            branchz="2. 23",
+            branchz_missing="2.",
+        )
+        assert self.stdout() == "1\n3\n"
+        expected = "line 2 didn't exit the module because the condition on line 2 was always true"
+        assert self.get_missing_arc_description(cov, 2, -1) == expected
+
     def test_with_with_lambda(self) -> None:
         self.check_coverage("""\
             from contextlib import nullcontext