update Metric.serialize to allow renaming of fields

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+## 20.2.0
+- Allow renaming of fields when serializing metrics ([mozilla/glean-dictionary#2309](https://github.com/mozilla/glean-dictionary/issues/2309))
+
 ## 20.1.0
 
 - Allow to overwrite date to check expiry against using the `SOURCE_DATE_EPOCH` environment variable ([bug 2052175](https://bugzilla.mozilla.org/show_bug.cgi?id=2052175))

glean_parser/metrics.py

@@ -165,7 +165,9 @@ def make_metric(
             **metric_info,
         )
 
-    def serialize(self) -> Dict[str, util.JSONType]:
+    def serialize(
+        self, rename_fields: Optional[Dict[str, str]] = None
+    ) -> Dict[str, util.JSONType]:
         """
         Serialize the metric back to JSON object model.
         """
@@ -178,6 +180,13 @@ def serialize(self) -> Dict[str, util.JSONType]:
                 d[key] = sorted(list(val))
             if isinstance(val, list) and len(val) and isinstance(val[0], enum.Enum):
                 d[key] = [x.name for x in val]
+
+        if rename_fields is not None:
+            for key, val in rename_fields.items():
+                if key in d:
+                    d[val] = d[key]
+                    del d[key]
+
         del d["name"]
         del d["category"]
         if not d["unit"]:
@@ -399,11 +408,13 @@ def __init__(self, *args, **kwargs):
             self.labels = None
         super().__init__(*args, **kwargs)
 
-    def serialize(self) -> Dict[str, util.JSONType]:
+    def serialize(
+        self, rename_fields: Optional[Dict[str, str]] = None
+    ) -> Dict[str, util.JSONType]:
         """
         Serialize the metric back to JSON object model.
         """
-        d = super().serialize()
+        d = super().serialize(rename_fields=rename_fields)
         d["labels"] = self.ordered_labels
         del d["ordered_labels"]
         return d
@@ -604,11 +615,13 @@ def __init__(self, *args, **kwargs):
             self.categories = None
         super().__init__(*args, **kwargs)
 
-    def serialize(self) -> Dict[str, util.JSONType]:
+    def serialize(
+        self, rename_fields: Optional[Dict[str, str]] = None
+    ) -> Dict[str, util.JSONType]:
         """
         Serialize the metric back to JSON object model.
         """
-        d = super().serialize()
+        d = super().serialize(rename_fields=rename_fields)
         d["keys"] = self.ordered_keys
         d["categories"] = self.ordered_categories
         del d["ordered_keys"]

tests/test_parser.py

@@ -1136,6 +1136,88 @@ def test_no_lint_sorted():
     assert all_objects.value["tags"]["tag"].no_lint == ["lint1", "lint2"]
 
 
+def test_allow_renaming_of_fields():
+    results = parser.parse_objects(
+        [
+            util.add_required(
+                {
+                    "category": {
+                        "metric": {
+                            "type": "object",
+                            "structure": {
+                                "type": "array",
+                                "items": {
+                                    "type": "object",
+                                    "properties": {
+                                        "prop_a": {
+                                            "type": "string",
+                                        },
+                                        "prop_b": {
+                                            "type": "boolean",
+                                        },
+                                    },
+                                },
+                            },
+                        },
+                    },
+                }
+            ),
+        ]
+    )
+    errs = list(results)
+    assert len(errs) == 0
+
+    metrics = {
+        metric.identifier(): metric.serialize(
+            rename_fields={"_generate_structure": "structure"}
+        )
+        for category, probes in results.value.items()
+        for probe_name, metric in probes.items()
+    }
+
+    expected = {
+        "category.metric": {
+            "bugs": ["http://bugzilla.mozilla.org/12345678"],
+            "data_reviews": ["https://example.com/review/"],
+            "defined_in": {"line": 3},
+            "description": "DESCRIPTION...",
+            "disabled": False,
+            "expires": "never",
+            "gecko_datapoint": "",
+            "in_session": False,
+            "lifetime": "ping",
+            "metadata": {},
+            "no_lint": [],
+            "notification_emails": ["nobody@example.com"],
+            "send_in_pings": ["metrics"],
+            "type": "object",
+            "version": 0,
+            "structure": {
+                "type": "array",
+                "items": {
+                    "type": "object",
+                    "properties": {
+                        "prop_a": {
+                            "type": "string",
+                        },
+                        "prop_b": {
+                            "type": "boolean",
+                        },
+                    },
+                },
+            },
+        },
+    }
+    expected_json = json.dumps(expected, sort_keys=True, indent=2)
+
+    out_json = json.dumps(
+        metrics,
+        sort_keys=True,
+        indent=2,
+    )
+    assert expected_json == out_json
+
+
 def test_no_internal_fields_exposed():
     """
     We accidentally exposed fields like `_config` and `_generate_enums` before.