Fix code and unit tests

Author: fcollonval

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/exemplar/exemplar_reservoir.py

@@ -68,7 +68,7 @@ def collect(self, point_attributes: Attributes) -> list[Exemplar]:
 class ExemplarBucket:
     def __init__(self) -> None:
         self.__value: Union[int, float] = 0
-        self.__attributes: Attributes = {}
+        self.__attributes: Attributes = None
         self.__time_unix_nano: int = 0
         self.__span_id: Optional[str] = None
         self.__trace_id: Optional[str] = None
@@ -98,11 +98,15 @@ def collect(self, point_attributes: Attributes) -> Exemplar | None:
         if not self.__offered:
             return None
 
-        current_attributes = {
-            k: v
-            for k, v in self.__attributes.items()
-            if k not in point_attributes
-        }
+        current_attributes = (
+            {
+                k: v
+                for k, v in self.__attributes.items()
+                if k not in point_attributes
+            }
+            if self.__attributes
+            else None
+        )
 
         exemplar = Exemplar(
             current_attributes,
@@ -157,7 +161,7 @@ def collect(self, point_attributes: Attributes) -> list[Exemplar]:
             ),
         )
         self._reset()
-        return [exemplars]
+        return [*exemplars]
 
     def _reset(self) -> None:
         """Reset the reservoir."""

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/instrument.py

@@ -141,8 +141,8 @@ def callback(
                         api_measurement.value,
                         time_unix_nano=time_ns(),
                         instrument=self,
-                        attributes=api_measurement.attributes,
                         context=api_measurement.context or get_current(),
+                        attributes=api_measurement.attributes,
                     )
             except Exception:  # pylint: disable=broad-exception-caught
                 _logger.exception(
@@ -173,8 +173,8 @@ def add(
                 amount,
                 time_unix_nano,
                 self,
-                attributes,
                 context or get_current(),
+                attributes,
             )
         )
 
@@ -197,8 +197,8 @@ def add(
                 amount,
                 time_unix_nano,
                 self,
-                attributes,
                 context or get_current(),
+                attributes,
             )
         )
 
@@ -245,8 +245,8 @@ def record(
                 amount,
                 time_unix_nano,
                 self,
-                attributes,
                 context or get_current(),
+                attributes,
             )
         )
 
@@ -269,8 +269,8 @@ def set(
                 amount,
                 time_unix_nano,
                 self,
-                attributes,
                 context or get_current(),
+                attributes,
             )
         )