remove: improve error message when trying to remove a package from a project without any dependencies

src/poetry/console/commands/remove.py

@@ -68,13 +68,13 @@ def handle(self) -> int:
         if group is None:
             # remove from all groups
             removed = set()
-            group_sections = [
-                (
-                    MAIN_GROUP,
-                    project_content.get("dependencies", []),
-                    poetry_content.get("dependencies", {}),
+            group_sections = []
+            project_dependencies = project_content.get("dependencies", [])
+            poetry_dependencies = poetry_content.get("dependencies", {})
+            if project_dependencies or poetry_dependencies:
+                group_sections.append(
+                    (MAIN_GROUP, project_dependencies, poetry_dependencies)
                 )
-            ]
             group_sections.extend(
                 (group_name, [], group_section.get("dependencies", {}))
                 for group_name, group_section in poetry_content.get("group", {}).items()

tests/console/commands/test_remove.py

@@ -358,6 +358,44 @@ def test_remove_canonicalized_named_removes_dependency_correctly(
     assert expected in string_content
 
 
+def test_remove_package_does_not_exist(
+    tester: CommandTester,
+    app: PoetryTestApplication,
+    repo: TestRepository,
+    command_tester_factory: CommandTesterFactory,
+) -> None:
+    repo.add_package(Package("foo", "2.0.0"))
+
+    original_content = app.poetry.file.read().as_string()
+
+    with pytest.raises(ValueError) as e:
+        tester.execute("foo")
+
+    assert str(e.value) == "The following packages were not found: foo"
+    assert app.poetry.file.read().as_string() == original_content
+
+
+def test_remove_package_no_dependencies(
+    tester: CommandTester,
+    app: PoetryTestApplication,
+    repo: TestRepository,
+    command_tester_factory: CommandTesterFactory,
+) -> None:
+    repo.add_package(Package("foo", "2.0.0"))
+
+    pyproject: dict[str, Any] = app.poetry.file.read()
+    assert "dependencies" not in pyproject["project"]
+    del pyproject["tool"]["poetry"]["dependencies"]
+    pyproject = cast("TOMLDocument", pyproject)
+    app.poetry.file.write(pyproject)
+    app.poetry.package._dependency_groups = {}
+
+    with pytest.raises(ValueError) as e:
+        tester.execute("foo")
+
+    assert str(e.value) == "The following packages were not found: foo"
+
+
 def test_remove_command_should_not_write_changes_upon_installer_errors(
     tester: CommandTester,
     app: PoetryTestApplication,