Improve readers Collect docs (#4361)

sdk/metric/manual_reader.go

@@ -118,8 +118,8 @@ func (mr *ManualReader) Shutdown(context.Context) error {
 	return err
 }
 
-// Collect gathers all metrics from the SDK and other Producers, calling any
-// callbacks necessary and stores the result in rm.
+// Collect gathers all metric data related to the Reader from
+// the SDK and other Producers and stores the result in rm.
 //
 // Collect will return an error if called after shutdown.
 // Collect will return an error if rm is a nil ResourceMetrics.

sdk/metric/manual_reader_test.go

@@ -80,25 +80,18 @@ func TestManualReaderCollect(t *testing.T) {
 	defer cancel()
 
 	tests := []struct {
-		name string
-
-		ctx             context.Context
-		resourceMetrics *metricdata.ResourceMetrics
-
+		name        string
+		ctx         context.Context
 		expectedErr error
 	}{
 		{
-			name: "with a valid context",
-
-			ctx:             context.Background(),
-			resourceMetrics: &metricdata.ResourceMetrics{},
+			name:        "with a valid context",
+			ctx:         context.Background(),
+			expectedErr: nil,
 		},
 		{
-			name: "with an expired context",
-
-			ctx:             expiredCtx,
-			resourceMetrics: &metricdata.ResourceMetrics{},
-
+			name:        "with an expired context",
+			ctx:         expiredCtx,
 			expectedErr: context.DeadlineExceeded,
 		},
 	}
@@ -117,7 +110,8 @@ func TestManualReaderCollect(t *testing.T) {
 			}, testM)
 			assert.NoError(t, err)
 
-			assert.Equal(t, tt.expectedErr, rdr.Collect(tt.ctx, tt.resourceMetrics))
+			rm := &metricdata.ResourceMetrics{}
+			assert.Equal(t, tt.expectedErr, rdr.Collect(tt.ctx, rm))
 		})
 	}
 }

sdk/metric/periodic_reader.go

@@ -237,8 +237,8 @@ func (r *PeriodicReader) collectAndExport(ctx context.Context) error {
 	return err
 }
 
-// Collect gathers and returns all metric data related to the Reader from
-// the SDK and other Producers and stores the result in rm. The returned metric
+// Collect gathers all metric data related to the Reader from
+// the SDK and other Producers and stores the result in rm. The metric
 // data is not exported to the configured exporter, it is left to the caller to
 // handle that if desired.
 //

sdk/metric/periodic_reader_test.go

@@ -424,25 +424,18 @@ func TestPeriodicReaderCollect(t *testing.T) {
 	defer cancel()
 
 	tests := []struct {
-		name string
-
-		ctx             context.Context
-		resourceMetrics *metricdata.ResourceMetrics
-
+		name        string
+		ctx         context.Context
 		expectedErr error
 	}{
 		{
-			name: "with a valid context",
-
-			ctx:             context.Background(),
-			resourceMetrics: &metricdata.ResourceMetrics{},
+			name:        "with a valid context",
+			ctx:         context.Background(),
+			expectedErr: nil,
 		},
 		{
-			name: "with an expired context",
-
-			ctx:             expiredCtx,
-			resourceMetrics: &metricdata.ResourceMetrics{},
-
+			name:        "with an expired context",
+			ctx:         expiredCtx,
 			expectedErr: context.DeadlineExceeded,
 		},
 	}
@@ -461,7 +454,8 @@ func TestPeriodicReaderCollect(t *testing.T) {
 			}, testM)
 			assert.NoError(t, err)
 
-			assert.Equal(t, tt.expectedErr, rdr.Collect(tt.ctx, tt.resourceMetrics))
+			rm := &metricdata.ResourceMetrics{}
+			assert.Equal(t, tt.expectedErr, rdr.Collect(tt.ctx, rm))
 		})
 	}
 }