fix: multi-line statements no longer confuse branch target descriptions. #1874 #1875

Author: nedbat

CHANGES.rst

@@ -23,6 +23,10 @@ upgrading your version of coverage.py.
 Unreleased
 ----------
 
+- Fix: some descriptions of missing branches in HTML and LCOV reports were
+  incorrect when multi-line statements were involved (`issue 1874`_ and `issue
+  1875`_).  These are now fixed.
+
 - Fix: Python 3.14 `defers evaluation of annotations <pep649_>`_ by moving them
   into separate code objects.  That code is rarely executed, so coverage.py
   would mark them as missing, as reported in `issue 1908`_.  Now they are
@@ -33,6 +37,8 @@ Unreleased
   understand the problem or the solution, but ``git bisect`` helped find it,
   and now it's fixed.
 
+.. _issue 1874: https://github.com/nedbat/coveragepy/issues/1874
+.. _issue 1875: https://github.com/nedbat/coveragepy/issues/1875
 .. _issue 1902: https://github.com/nedbat/coveragepy/issues/1902
 .. _issue 1908: https://github.com/nedbat/coveragepy/issues/1908
 .. _pep649: https://docs.python.org/3.14/whatsnew/3.14.html#pep-649-deferred-evaluation-of-annotations

coverage/parser.py

@@ -684,7 +684,6 @@ def __init__(
     ) -> None:
         self.filename = filename
         self.root_node = root_node
-        # TODO: I think this is happening in too many places.
         self.statements = {multiline.get(l, l) for l in statements}
         self.multiline = multiline
 
@@ -812,9 +811,10 @@ def line_for_node(self, node: ast.AST) -> TLineNo:
             getattr(self, "_line__" + node_name, None),
         )
         if handler is not None:
-            return handler(node)
+            line = handler(node)
         else:
-            return node.lineno      # type: ignore[attr-defined, no-any-return]
+            line = node.lineno      # type: ignore[attr-defined]
+        return self.multiline.get(line, line)
 
     # First lines: _line__*
     #
@@ -936,8 +936,7 @@ def process_body(
         # the next node.
         for body_node in body:
             lineno = self.line_for_node(body_node)
-            first_line = self.multiline.get(lineno, lineno)
-            if first_line not in self.statements:
+            if lineno not in self.statements:
                 maybe_body_node = self.find_non_missing_node(body_node)
                 if maybe_body_node is None:
                     continue
@@ -961,8 +960,7 @@ def find_non_missing_node(self, node: ast.AST) -> ast.AST | None:
         # means we can avoid a function call in the 99.9999% case of not
         # optimizing away statements.
         lineno = self.line_for_node(node)
-        first_line = self.multiline.get(lineno, lineno)
-        if first_line in self.statements:
+        if lineno in self.statements:
             return node
 
         missing_fn = cast(
@@ -1110,8 +1108,6 @@ def _handle_decorated(self, node: ast.FunctionDef) -> set[ArcStart]:
             # not what we'd think of as the first line in the statement, so map
             # it to the first one.
             assert node.body, f"Oops: {node.body = } in {self.filename}@{node.lineno}"
-            body_start = self.line_for_node(node.body[0])
-            body_start = self.multiline.get(body_start, body_start)
         # The body is handled in collect_arcs.
         assert last is not None
         return {ArcStart(last)}

coverage/results.py

@@ -34,7 +34,8 @@ def analysis_from_file_reporter(
 
     if has_arcs:
         arc_possibilities_set = file_reporter.arcs()
-        arcs = data.arcs(filename) or []
+        arcs: Iterable[TArc] = data.arcs(filename) or []
+        arcs = file_reporter.translate_arcs(arcs)
 
         # Reduce the set of arcs to the ones that could be branches.
         dests = collections.defaultdict(set)

tests/test_lcov.py

@@ -558,3 +558,33 @@ def test_always_raise(self) -> None:
             """)
         actual_result = self.get_lcov_report_content()
         assert expected_result == actual_result
+
+    def test_multiline_conditions(self) -> None:
+        self.make_file("multi.py", """\
+            def fun(x):
+                if (
+                    x
+                ):
+                    print("got here")
+            """)
+        cov = coverage.Coverage(source=".", branch=True)
+        self.start_import_stop(cov, "multi")
+        cov.lcov_report()
+        lcov = self.get_lcov_report_content()
+        assert "BRDA:2,0,return from function 'fun',-" in lcov
+
+    def test_module_exit(self) -> None:
+        self.make_file("modexit.py", """\
+            #! /usr/bin/env python
+            def foo():
+                return bar(
+                )
+            if "x" == "y":  # line 5
+                foo()
+            """)
+        cov = coverage.Coverage(source=".", branch=True)
+        self.start_import_stop(cov, "modexit")
+        cov.lcov_report()
+        lcov = self.get_lcov_report_content()
+        print(lcov)
+        assert "BRDA:5,0,exit the module,1" in lcov