python_requirements_info - fail when version operator used without version (#3785)

* python_requirements_info - fail when version operator used without version

* added changelog fragment

* simplified way of achieving the same result

changelogs/fragments/3785-python_requirements_info-versionless-op.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+    - python_requirements_info - fails if version operator used without version (https://github.com/ansible-collections/community.general/pull/3785).

plugins/modules/system/python_requirements_info.py

@@ -121,7 +121,7 @@ def main():
             python_version=sys.version,
             python_system_path=sys.path,
         )
-    pkg_dep_re = re.compile(r'(^[a-zA-Z][a-zA-Z0-9_-]+)(==|[><]=?)?([0-9.]+)?$')
+    pkg_dep_re = re.compile(r'(^[a-zA-Z][a-zA-Z0-9_-]+)(?:(==|[><]=?)([0-9.]+))?$')
 
     results = dict(
         not_found=[],
@@ -131,7 +131,7 @@ def main():
 
     for dep in (module.params.get('dependencies') or []):
         match = pkg_dep_re.match(dep)
-        if match is None:
+        if not match:
             module.fail_json(msg="Failed to parse version requirement '{0}'. Must be formatted like 'ansible>2.6'".format(dep))
         pkg, op, version = match.groups()
         if op is not None and op not in operations:

tests/integration/targets/python_requirements_info/tasks/main.yml

@@ -25,3 +25,15 @@
     that:
       - "'installed' in dep_info.valid.pip"
       - "'notreal' in dep_info.not_found"
+
+- name: wrong specs
+  python_requirements_info:
+    dependencies:
+      - ansible<
+  register: wrong_spec1
+  ignore_errors: true
+
+- name: ensure wrong specs return error
+  assert:
+    that:
+      - wrong_spec1 is failed