feat: add check for existence of python scripts in user-defined handler (#1908)

**Issue number:** ADDON-82908

### PR Type

**What kind of change does this PR introduce?**
* [x] Feature
* [ ] Bug Fix
* [ ] Refactoring (no functional or API changes)
* [ ] Documentation Update
* [ ] Maintenance (dependency updates, CI, etc.)

## Summary

### Changes

Added a check in `global_config_validator.py` for existence of python
scripts mentioned in user-defined handler.
### User experience

Add-on build would fail if python script mentioned under
`options/restHandlers` is not present in add-ons bin directory.

## Checklist

If an item doesn't apply to your changes, leave it unchecked.

### Review

* [x] self-review - I have performed a self-review of this change
according to the [development
guidelines](https://splunk.github.io/addonfactory-ucc-generator/contributing/#development-guidelines)
* [ ] Changes are documented. The documentation is understandable,
examples work [(more
info)](https://splunk.github.io/addonfactory-ucc-generator/contributing/#documentation-guidelines)
* [x] PR title and description follows the [contributing
principles](https://splunk.github.io/addonfactory-ucc-generator/contributing/#pull-requests)
* [ ] meeting - I have scheduled a meeting or recorded a demo to explain
these changes (if there is a video, put a link below and in the ticket)

### Tests

See [the testing
doc](https://splunk.github.io/addonfactory-ucc-generator/contributing/#build-and-test).

* [x] Unit - tests have been added/modified to cover the changes
* [x] Smoke - tests have been added/modified to cover the changes
* [ ] UI - tests have been added/modified to cover the changes
* [x] coverage - I have checked the code coverage of my changes [(see
more)](https://splunk.github.io/addonfactory-ucc-generator/contributing/#checking-the-code-coverage)

**Demo/meeting:**

*Reviewers are encouraged to request meetings or demos if any part of
the change is unclear*

Author: hetangmodi-crest

splunk_add_on_ucc_framework/global_config_validator.py

@@ -840,6 +840,19 @@ def _validate_usage_of_placeholder(self) -> None:
                         exc_msg % ("input service", service["name"])
                     )
 
+    def _validate_user_defined_rest_handler_file(self) -> None:
+        if self._global_config.content.get("options"):
+            for restHandler in self._global_config.content["options"]["restHandlers"]:
+                if restHandler.get("registerHandler"):
+                    file_path = os.path.join(
+                        self._source_dir, "bin", restHandler["registerHandler"]["file"]
+                    )
+                    if not os.path.isfile(file_path):
+                        raise GlobalConfigValidatorException(
+                            f"{restHandler['registerHandler']['file']} is not present in "
+                            f"`{os.path.join(self._source_dir, 'bin')}` directory. Please ensure the file exists."
+                        )
+
     def validate(self) -> None:
         self._validate_config_against_schema()
         if self._global_config.has_pages():
@@ -858,6 +871,7 @@ def validate(self) -> None:
             self._validate_usage_of_placeholder()
         self._validate_alerts()
         self._validate_meta_default_view()
+        self._validate_user_defined_rest_handler_file()
 
 
 def should_warn_on_empty_validators(entity: Dict[str, Any]) -> bool:

tests/testdata/test_addons/package_global_config_configuration/package/bin/someFile.py

@@ -0,0 +1 @@
+# This is a dummy python file for user-defined endpoint `Splunk_TA_Example_full` defined in options.

tests/unit/test_check_globalConfig.py

@@ -25,6 +25,7 @@ def test_build_addon_from_global_config(config_file, caplog):
         "valid_config.json",
         "valid_config_with_custom_dashboard.json",
         "valid_config_only_custom_dashboard.json",
+        "valid_config_logging_with_user_defined_handlers.json",
     ]:
         pytest.skip("As these files need external dependency.")
 

tests/unit/test_global_config_validator.py

@@ -82,6 +82,10 @@ def test_autocompletefields_children_support_integer_values():
             "invalid_config_for_custom_search_command.json",
             "generatetext.py is not present in `bin` directory. Please ensure the file exists.",
         ),
+        (
+            "invalid_config_with_user_defined_rest_handlers.json",
+            "file1.py is not present in `bin` directory. Please ensure the file exists.",
+        ),
         (
             "invalid_config_no_configuration_tabs.json",
             "[] is too short",

tests/unit/testdata/invalid_config_with_user_defined_rest_handlers.json

@@ -0,0 +1,28 @@
+{
+    "options": {
+        "restHandlers": [
+            {
+                "name": "name1",
+                "endpoint": "endpoint1",
+                "handlerType": "EAI",
+                "resourcePresent": true,
+                "registerHandler": {
+                    "file": "file1.py",
+                    "actions": [
+                        "list"
+                    ]
+                },
+                "capabilities": {
+                    "post": "list_storage_passwords"
+                }
+            }
+        ]
+    },
+    "meta": {
+        "name": "Splunk_TA_UCCExample",
+        "restRoot": "splunk_ta_uccexample",
+        "version": "1.0.0",
+        "displayName": "Splunk UCC test Add-on",
+        "schemaVersion": "0.0.3"
+    }
+}