Import test: improve docs, add more tests

docs/docsite/rst/dev_guide/testing/sanity/import.rst

@@ -1,5 +1,68 @@
 import
 ======
 
-All Python imports in ``lib/ansible/modules/`` and ``lib/ansible/module_utils/`` which are not from the Python standard library
-must be imported in a try/except ImportError block.
+Ansible allows unchecked imports of some libraries from specific directories, listed at the bottom of this section. Import all other Python libraries in a try/except ImportError block to support sanity tests such as ``validate-modules`` and to allow Ansible to give better error messages to the user. To import a library in a try/except ImportError block:
+
+1. In modules:
+
+   .. code-block:: python
+
+       # Instead of 'import another_library', do:
+
+       import traceback
+
+       try:
+           import another_library
+       except ImportError:
+           HAS_ANOTHER_LIBRARY = False
+           ANOTHER_LIBRARY_IMPORT_ERROR = traceback.format_exc()
+       else:
+           HAS_ANOTHER_LIBRARY = True
+
+
+       # Later in module code:
+
+       module = AnsibleModule(...)
+
+       if not HAS_ANOTHER_LIBRARY:
+           # Needs: from ansible.module_utils.basic import missing_required_lib
+           module.fail_json(
+               msg=missing_required_lib('another_library'),
+               exception=ANOTHER_LIBRARY_IMPORT_ERROR)
+
+2. In plugins:
+
+   .. code-block:: python
+
+       # Instead of 'import another_library', do:
+
+       from ansible.module_utils.six import raise_from
+
+       try:
+           import another_library
+       except ImportError as imp_exc:
+           ANOTHER_LIBRARY_IMPORT_ERROR = imp_exc
+       else:
+           ANOTHER_LIBRARY_IMPORT_ERROR = None
+
+
+       # Later in plugin code, for example in __init__ of the plugin:
+
+       if ANOTHER_LIBRARY_IMPORT_ERROR:
+           raise_from(
+               AnsibleError('another_library must be installed to use this plugin'),
+               ANOTHER_LIBRARY_IMPORT_ERROR)
+           # If you target only newer Python 3 versions, you can also use the
+           # 'raise ... from ...' syntax.
+
+Ansible allows the following unchecked imports from these specific directories:
+
+* ansible-core:
+
+  * For ``lib/ansible/modules/`` and ``lib/ansible/module_utils/``, unchecked imports are only allowed from the Python standard library;
+  * For ``lib/ansible/plugins/``, unchecked imports are only allowed from the Python standard library, from dependencies of ansible-core, and from ansible-core itself;
+
+* collections:
+
+  * For ``plugins/modules/`` and ``plugins/module_utils/``, unchecked imports are only allowed from the Python standard library;
+  * For other directories in ``plugins/`` (see `the community collection requirements <https://github.com/ansible-collections/overview/blob/main/collection_requirements.rst#modules-plugins>`_ for a list), unchecked imports are only allowed from the Python standard library, from dependencies of ansible-core, and from ansible-core itself.

test/integration/targets/ansible-test/ansible_collections/ns/col/plugins/lookup/bad.py

@@ -0,0 +1,31 @@
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+DOCUMENTATION = '''
+name: bad
+short_description: Bad lookup
+description: A bad lookup.
+author:
+  - Ansible Core Team
+'''
+
+EXAMPLES = '''
+- debug:
+    msg: "{{ lookup('ns.col.bad') }}"
+'''
+
+RETURN = ''' # '''
+
+from ansible.plugins.lookup import LookupBase
+from ansible import constants
+
+import lxml
+
+
+class LookupModule(LookupBase):
+    def run(self, terms, variables, **kwargs):
+        self.set_options(var_options=variables, direct=kwargs)
+
+        return terms

test/integration/targets/ansible-test/ansible_collections/ns/col/plugins/lookup/world.py

@@ -0,0 +1,29 @@
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+DOCUMENTATION = '''
+name: world
+short_description: World lookup
+description: A world lookup.
+author:
+  - Ansible Core Team
+'''
+
+EXAMPLES = '''
+- debug:
+    msg: "{{ lookup('ns.col.world') }}"
+'''
+
+RETURN = ''' # '''
+
+from ansible.plugins.lookup import LookupBase
+from ansible import constants
+
+
+class LookupModule(LookupBase):
+    def run(self, terms, variables, **kwargs):
+        self.set_options(var_options=variables, direct=kwargs)
+
+        return terms

test/integration/targets/ansible-test/ansible_collections/ns/col/plugins/random_directory/bad.py

@@ -0,0 +1,8 @@
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+# This is not an allowed import, but since this file is in a plugins/ subdirectory that is not checked,
+# the import sanity test will not complain.
+import lxml

test/integration/targets/ansible-test/ansible_collections/ns/col/tests/sanity/ignore.txt

@@ -1,5 +1,6 @@
 plugins/modules/bad.py import
 plugins/modules/bad.py pylint:ansible-bad-module-import
+plugins/lookup/bad.py import
 tests/integration/targets/hello/files/bad.py pylint:ansible-bad-function
 tests/integration/targets/hello/files/bad.py pylint:ansible-bad-import
 tests/integration/targets/hello/files/bad.py pylint:ansible-bad-import-from

test/integration/targets/ansible-test/collection-tests/coverage.sh

@@ -7,7 +7,13 @@ cd "${WORK_DIR}/ansible_collections/ns/col"
 
 # rename the sanity ignore file to match the current ansible version and update import ignores with the python version
 ansible_version="$(python -c 'import ansible.release; print(".".join(ansible.release.__version__.split(".")[:2]))')"
-sed "s/ import$/ import-${ANSIBLE_TEST_PYTHON_VERSION}/;" < "tests/sanity/ignore.txt" > "tests/sanity/ignore-${ansible_version}.txt"
+if [ "${ANSIBLE_TEST_PYTHON_VERSION}" == "2.6" ]; then
+    # Non-module/module_utils plugins are not checked on this remote-only Python versions
+    sed "s/ import$/ import-${ANSIBLE_TEST_PYTHON_VERSION}/;" < "tests/sanity/ignore.txt" | grep -v 'plugins/[^m].* import' > "tests/sanity/ignore-${ansible_version}.txt"
+else
+    sed "s/ import$/ import-${ANSIBLE_TEST_PYTHON_VERSION}/;" < "tests/sanity/ignore.txt" > "tests/sanity/ignore-${ansible_version}.txt"
+fi
+cat "tests/sanity/ignore-${ansible_version}.txt"
 
 # common args for all tests
 common=(--venv --color --truncate 0 "${@}")

test/integration/targets/ansible-test/collection-tests/venv.sh

@@ -7,7 +7,13 @@ cd "${WORK_DIR}/ansible_collections/ns/col"
 
 # rename the sanity ignore file to match the current ansible version and update import ignores with the python version
 ansible_version="$(python -c 'import ansible.release; print(".".join(ansible.release.__version__.split(".")[:2]))')"
-sed "s/ import$/ import-${ANSIBLE_TEST_PYTHON_VERSION}/;" < "tests/sanity/ignore.txt" > "tests/sanity/ignore-${ansible_version}.txt"
+if [ "${ANSIBLE_TEST_PYTHON_VERSION}" == "2.6" ]; then
+    # Non-module/module_utils plugins are not checked on this remote-only Python versions
+    sed "s/ import$/ import-${ANSIBLE_TEST_PYTHON_VERSION}/;" < "tests/sanity/ignore.txt" | grep -v 'plugins/[^m].* import' > "tests/sanity/ignore-${ansible_version}.txt"
+else
+    sed "s/ import$/ import-${ANSIBLE_TEST_PYTHON_VERSION}/;" < "tests/sanity/ignore.txt" > "tests/sanity/ignore-${ansible_version}.txt"
+fi
+cat "tests/sanity/ignore-${ansible_version}.txt"
 
 # common args for all tests
 # each test will be run in a separate venv to verify that requirements have been properly specified