new: Add support for output overrides and add domains zone-file override (#449)

## 📝 Description

This change introduces a new output override system that allows us to
modularly add custom output logic for specific generated commands. This
is useful for cleaning up outputs for endpoints with responses that may
be too complicated to account for in the spec parser.

Author: lgarber-akamai

linodecli/operation.py

@@ -11,6 +11,8 @@
 
 from linodecli.helpers import handle_url_overrides
 
+from .overrides import OUTPUT_OVERRIDES
+
 
 def parse_boolean(value):
     """
@@ -346,6 +348,12 @@ def process_response_json(
         if self.response_model is None:
             return
 
+        override = OUTPUT_OVERRIDES.get(
+            (self.command, self.action, handler.mode)
+        )
+        if override is not None and not override(self, handler, json):
+            return
+
         json = self.response_model.fix_json(json)
 
         handler.print(self.response_model, json)

linodecli/overrides.py

@@ -0,0 +1,39 @@
+"""
+Contains wrappers for overriding certain pieces of command-handling logic.
+This allows us to easily alter per-command outputs, etc. without making
+large changes to the OpenAPI spec.
+"""
+
+from linodecli.output import OutputMode
+
+OUTPUT_OVERRIDES = {}
+
+
+def output_override(command: str, action: str, output_mode: OutputMode):
+    """
+    A decorator function for adding a new output override handler.
+
+    Output override functions should have the following signature::
+
+        @output_override("command", "action", OutputMode.{output_mode})
+        def my_override(operation, output_handler, json_data) -> bool:
+            ...
+
+    If the returned bool is False, the original output functionality will be skipped.
+    Otherwise, the original output functionality will continue as normal.
+    """
+
+    def inner(func):
+        OUTPUT_OVERRIDES[(command, action, output_mode)] = func
+
+    return inner
+
+
+@output_override("domains", "zone-file", OutputMode.delimited)
+def handle_domains_zone_file(operation, output_handler, json_data) -> bool:
+    # pylint: disable=unused-argument
+    """
+    Fix for output of 'linode-cli domains zone-file --text {id}'.
+    """
+    print("\n".join(json_data["zone_file"]))
+    return False

tests/unit/test_overrides.py

@@ -0,0 +1,59 @@
+import contextlib
+import io
+from unittest.mock import patch
+
+from linodecli import ModelAttr, OutputMode, ResponseModel
+from linodecli.overrides import OUTPUT_OVERRIDES
+
+
+class TestOverrides:
+    """
+    Unit tests for linodecli.overrides
+    """
+
+    def test_domains_zone_file(self, mock_cli, list_operation):
+        response_json = {"zone_file": ["line 1", "line 2"]}
+        override_signature = ("domains", "zone-file", OutputMode.delimited)
+
+        list_operation.response_model = ResponseModel(
+            [ModelAttr("zone_file", False, False, "array", item_type="string")]
+        )
+        list_operation.command = "domains"
+        list_operation.action = "zone-file"
+        mock_cli.output_handler.mode = OutputMode.delimited
+
+        stdout_buf = io.StringIO()
+
+        with contextlib.redirect_stdout(stdout_buf):
+            list_operation.process_response_json(
+                response_json, mock_cli.output_handler
+            )
+
+        assert stdout_buf.getvalue() == "line 1\nline 2\n"
+
+        # Validate that the override will continue execution if it returns true
+        def patch_func(*a):
+            OUTPUT_OVERRIDES[override_signature](*a)
+            return True
+
+        with patch(
+            "linodecli.operation.OUTPUT_OVERRIDES",
+            {override_signature: patch_func},
+        ), patch.object(mock_cli.output_handler, "print") as p:
+            list_operation.process_response_json(
+                response_json, mock_cli.output_handler
+            )
+            assert p.called
+
+        # Change the action to bypass the override
+        stdout_buf = io.StringIO()
+
+        list_operation.action = "zone-notfile"
+        mock_cli.output_handler.mode = OutputMode.delimited
+
+        with contextlib.redirect_stdout(stdout_buf):
+            list_operation.process_response_json(
+                response_json, mock_cli.output_handler
+            )
+
+        assert stdout_buf.getvalue() != "line 1\nline 2\n"