correctly handle multiple asserts

_pytest/assertrewrite.py

@@ -99,19 +99,22 @@ class AssertionRewriter(ast.NodeVisitor):
             node = nodes.popleft()
             for name, field in ast.iter_fields(node):
                 if isinstance(field, list):
+                    new = []
                     for i, child in enumerate(field):
                         if isinstance(child, ast.Assert):
+                            # Transform assert.
+                            new.extend(self.visit(child))
                             asserts.append((field, i, child))
-                        elif isinstance(child, ast.AST):
-                            nodes.append(child)
+                        else:
+                            new.append(child)
+                            if isinstance(child, ast.AST):
+                                nodes.append(child)
+                    setattr(node, name, new)
                 elif (isinstance(field, ast.AST) and
                       # Don't recurse into expressions as they can't contain
                       # asserts.
                       not isinstance(field, ast.expr)):
                     nodes.append(field)
-        # Transform asserts.
-        for parent, pos, assert_ in asserts:
-            parent[pos:pos + 1] = self.visit(assert_)
 
     def variable(self):
         """Get a new variable."""

testing/test_assertrewrite.py

@@ -196,6 +196,11 @@ class TestAssertionRewrite:
             a, b, c = range(3)
             assert a < b <= c
         getmsg(f, must_pass=True)
+        def f():
+            a, b, c = range(3)
+            assert a < b
+            assert b < c
+        getmsg(f, must_pass=True)
 
     def test_len(self):
         def f():