refactor error creation and tests

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

model/histogram/float_histogram.go

@@ -830,7 +830,7 @@ func (h *FloatHistogram) Validate() error {
 			return errors.New("histogram with exponential schema must not have custom bounds")
 		}
 	default:
-		return fmt.Errorf("schema %d: %w", h.Schema, ErrHistogramsInvalidSchema)
+		return InvalidSchemaError(h.Schema)
 	}
 	err := checkHistogramBuckets(h.PositiveBuckets, &pCount, false)
 	if err != nil {

model/histogram/generic.go

@@ -42,6 +42,10 @@ var (
 	ErrHistogramsInvalidSchema        = fmt.Errorf("histogram has an invalid schema, which must be between %d and %d for exponential buckets, or %d for custom buckets", ExponentialSchemaMin, ExponentialSchemaMax, CustomBucketsSchema)
 )
 
+func InvalidSchemaError(s int32) error {
+	return fmt.Errorf("%w, got schema %d", ErrHistogramsInvalidSchema, s)
+}
+
 func IsCustomBucketsSchema(s int32) bool {
 	return s == CustomBucketsSchema
 }

model/histogram/histogram.go

@@ -457,7 +457,7 @@ func (h *Histogram) Validate() error {
 			return errors.New("histogram with exponential schema must not have custom bounds")
 		}
 	default:
-		return fmt.Errorf("schema %d: %w", h.Schema, ErrHistogramsInvalidSchema)
+		return InvalidSchemaError(h.Schema)
 	}
 	err := checkHistogramBuckets(h.PositiveBuckets, &pCount, true)
 	if err != nil {

model/histogram/histogram_test.go

@@ -1569,13 +1569,13 @@ func TestHistogramValidation(t *testing.T) {
 			h: &Histogram{
 				Schema: 10,
 			},
-			errMsg: `schema 10: histogram has an invalid schema, which must be between -4 and 8 for exponential buckets, or -53 for custom buckets`,
+			errMsg: `histogram has an invalid schema, which must be between -4 and 8 for exponential buckets, or -53 for custom buckets, got schema 10`,
 		},
 		"schema too low": {
 			h: &Histogram{
 				Schema: -10,
 			},
-			errMsg: `schema -10: histogram has an invalid schema, which must be between -4 and 8 for exponential buckets, or -53 for custom buckets`,
+			errMsg: `histogram has an invalid schema, which must be between -4 and 8 for exponential buckets, or -53 for custom buckets, got schema -10`,
 		},
 	}
 

storage/remote/codec.go

@@ -475,7 +475,7 @@ func validateHistogramSchema(h *prompb.Histogram) error {
 	if histogram.IsValidSchema(h.Schema) {
 		return nil
 	}
-	return return fmt.Errorf("%w, got schema %d", h.Schema, histogram.ErrHistogramsInvalidSchema)
+	return histogram.InvalidSchemaError(h.Schema)
 }
 
 func getHistogramValType(h *prompb.Histogram) chunkenc.ValueType {

tsdb/chunkenc/float_histogram.go

@@ -956,7 +956,7 @@ func (it *floatHistogramIterator) Next() ValueType {
 		}
 
 		if !histogram.IsValidSchema(schema) {
-			it.err = fmt.Errorf("invalid histogram schema %d", schema)
+			it.err = histogram.InvalidSchemaError(schema)
 			return ValNone
 		}
 

tsdb/chunkenc/float_histogram_test.go

@@ -1488,7 +1488,7 @@ func TestFloatHistogramIteratorFailIfSchemaInValid(t *testing.T) {
 
 			it := c.Iterator(nil)
 			require.Equal(t, ValNone, it.Next())
-			require.EqualError(t, it.Err(), fmt.Sprintf("invalid histogram schema %d", schema))
+			require.ErrorIs(t, it.Err(), histogram.ErrHistogramsInvalidSchema)
 		})
 	}
 }

tsdb/chunkenc/histogram.go

@@ -1079,7 +1079,7 @@ func (it *histogramIterator) Next() ValueType {
 		}
 
 		if !histogram.IsValidSchema(schema) {
-			it.err = fmt.Errorf("invalid histogram schema %d", schema)
+			it.err = histogram.InvalidSchemaError(schema)
 			return ValNone
 		}
 

tsdb/chunkenc/histogram_test.go

@@ -1844,7 +1844,7 @@ func TestHistogramIteratorFailIfSchemaInValid(t *testing.T) {
 
 			it := c.Iterator(nil)
 			require.Equal(t, ValNone, it.Next())
-			require.EqualError(t, it.Err(), fmt.Sprintf("invalid histogram schema %d", schema))
+			require.ErrorIs(t, it.Err(), histogram.ErrHistogramsInvalidSchema)
 		})
 	}
 }