feat!: DISABLED is a successful evaluation (still defaults) (#395)

* feat(flagd-core): add disabled flag evaluation e2e BDD scenarios

Signed-off-by: Jonathan Norris <jonathan.norris@dynatrace.com>

* chore: bump flagd-testbed submodule to v3.8.0

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

* feat(flagd): RPC resolver substitutes caller default on reason=DISABLED

Mirrors the existing reason=DEFAULT substitution: when the server returns an empty variant alongside DISABLED, surface the caller's code default value rather than the zero proto value.

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

* fix(flagd): RPC Object resolver tolerates missing value field

MessageToDict drops the value field entirely for DISABLED responses (no value is sent). Fall back to the caller's default_value via .get() instead of raising KeyError; the substitution branch then surfaces the default with reason=DISABLED.

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

* style(flagd): apply ruff format to DISABLED guard

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

* chore(flagd-core): drop redundant disabled.feature and test_disabled.py

v3.8.0 of the test-harness submodule already bundles disabled.feature in evaluator/gherkin/ and the disabled-* flags in evaluator/flags/testkit-flags.json. The hatch build hook auto-copies both into the testkit, so test_evaluator.py picks the disabled scenarios up via get_features_path() without any local files.

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

* Apply suggestion from @toddbaert

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

---------

Signed-off-by: Jonathan Norris <jonathan.norris@dynatrace.com>
Signed-off-by: Todd Baert <todd.baert@dynatrace.com>
Co-authored-by: Todd Baert <todd.baert@dynatrace.com>

Author: jonathannorris

providers/openfeature-provider-flagd/openfeature/test-harness

@@ -409,9 +409,10 @@ def _resolve(  # noqa: PLR0915 C901
                     flag_key=flag_key, context=context
                 )
                 response = self.stub.ResolveObject(request, **call_args)
-                value = MessageToDict(response, preserving_proto_field_name=True)[
-                    "value"
-                ]
+                # DISABLED responses omit the value field entirely; fall back to default_value
+                value = MessageToDict(response, preserving_proto_field_name=True).get(
+                    "value", default_value
+                )
             elif flag_type == FlagType.FLOAT:
                 request = evaluation_pb2.ResolveFloatRequest(
                     flag_key=flag_key, context=context
@@ -443,8 +444,12 @@ def _resolve(  # noqa: PLR0915 C901
             raise GeneralError(message) from e
 
         # When no default variant is configured, the server returns an empty/zero proto
-        # value with reason=DEFAULT. In that case, return the caller's code default value.
-        if response.reason == Reason.DEFAULT and not response.variant:
+        # value with reason=DEFAULT. For DISABLED flags the server omits the variant too.
+        # In both cases, return the caller's code default value.
+        if (
+            response.reason in (Reason.DEFAULT, Reason.DISABLED)
+            and not response.variant
+        ):
             value = default_value
 
         # Got a valid flag and valid type. Return it.