fix testcase, raise exception on failure

Author: dimbleby

src/poetry/packages/locker.py

@@ -254,10 +254,7 @@ def __walk_dependencies(
             )
 
             if not locked_package:
-                # Should normally be able to satisfy all requirements, but this case is
-                # permissible eg if we encounter a dev dependency when walking the
-                # non-dev dependencies.
-                continue
+                raise RuntimeError(f"Dependency walk failed at {requirement}")
 
             # create dependency from locked package to retain dependency metadata
             # if this is not done, we can end-up with incorrect nested dependencies

tests/utils/test_exporter.py

@@ -1657,8 +1657,6 @@ def test_exporter_exports_requirements_txt_with_legacy_packages_trusted_host(
         (
             False,
             [
-                'bar==1.2.2 ; python_version >= "2.7" and python_version < "2.8" or'
-                ' python_version >= "3.6" and python_version < "4.0"',
                 'foo==1.2.1 ; python_version >= "2.7" and python_version < "2.8" or'
                 ' python_version >= "3.6" and python_version < "4.0"',
             ],
@@ -1681,7 +1679,7 @@ def test_exporter_exports_requirements_txt_with_dev_extras(
                 {
                     "name": "bar",
                     "version": "1.2.2",
-                    "category": "main",
+                    "category": "dev",
                     "optional": False,
                     "python-versions": "*",
                     "dependencies": {