Export single ith test histogram generation functions (#11911)

* Export single ith test histogram generation functions

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

* Do not set counter reset hint for non-gauge histograms individually

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

* Apply suggestions from code review

Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>
Signed-off-by: George Krajcsovits <krajorama@users.noreply.github.com>

---------

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
Signed-off-by: George Krajcsovits <krajorama@users.noreply.github.com>
Co-authored-by: Ganesh Vernekar <ganeshvern@gmail.com>

tsdb/head.go

@@ -2040,36 +2040,18 @@ func (h *Head) updateWALReplayStatusRead(current int) {
 
 func GenerateTestHistograms(n int) (r []*histogram.Histogram) {
 	for i := 0; i < n; i++ {
-		h := histogram.Histogram{
-			Count:         10 + uint64(i*8),
-			ZeroCount:     2 + uint64(i),
-			ZeroThreshold: 0.001,
-			Sum:           18.4 * float64(i+1),
-			Schema:        1,
-			PositiveSpans: []histogram.Span{
-				{Offset: 0, Length: 2},
-				{Offset: 1, Length: 2},
-			},
-			PositiveBuckets: []int64{int64(i + 1), 1, -1, 0},
-			NegativeSpans: []histogram.Span{
-				{Offset: 0, Length: 2},
-				{Offset: 1, Length: 2},
-			},
-			NegativeBuckets: []int64{int64(i + 1), 1, -1, 0},
-		}
+		h := GenerateTestHistogram(i)
 		if i > 0 {
 			h.CounterResetHint = histogram.NotCounterReset
 		}
-		r = append(r, &h)
+		r = append(r, h)
 	}
 	return r
 }
 
-func GenerateTestGaugeHistograms(n int) (r []*histogram.Histogram) {
-	for x := 0; x < n; x++ {
-		i := rand.Intn(n)
-		r = append(r, &histogram.Histogram{
-			CounterResetHint: histogram.GaugeType,
+// Generates a test histogram, it is up to the user to set any known counter reset hint.
+func GenerateTestHistogram(i int) *histogram.Histogram {
+	return &histogram.Histogram{
 		Count:         10 + uint64(i*8),
 		ZeroCount:     2 + uint64(i),
 		ZeroThreshold: 0.001,
@@ -2085,44 +2067,36 @@ func GenerateTestGaugeHistograms(n int) (r []*histogram.Histogram) {
 			{Offset: 1, Length: 2},
 		},
 		NegativeBuckets: []int64{int64(i + 1), 1, -1, 0},
-		})
+	}
+}
+
+func GenerateTestGaugeHistograms(n int) (r []*histogram.Histogram) {
+	for x := 0; x < n; x++ {
+		r = append(r, GenerateTestGaugeHistogram(rand.Intn(n)))
 	}
 	return r
 }
 
+func GenerateTestGaugeHistogram(i int) *histogram.Histogram {
+	h := GenerateTestHistogram(i)
+	h.CounterResetHint = histogram.GaugeType
+	return h
+}
+
 func GenerateTestFloatHistograms(n int) (r []*histogram.FloatHistogram) {
 	for i := 0; i < n; i++ {
-		h := histogram.FloatHistogram{
-			Count:         10 + float64(i*8),
-			ZeroCount:     2 + float64(i),
-			ZeroThreshold: 0.001,
-			Sum:           18.4 * float64(i+1),
-			Schema:        1,
-			PositiveSpans: []histogram.Span{
-				{Offset: 0, Length: 2},
-				{Offset: 1, Length: 2},
-			},
-			PositiveBuckets: []float64{float64(i + 1), float64(i + 2), float64(i + 1), float64(i + 1)},
-			NegativeSpans: []histogram.Span{
-				{Offset: 0, Length: 2},
-				{Offset: 1, Length: 2},
-			},
-			NegativeBuckets: []float64{float64(i + 1), float64(i + 2), float64(i + 1), float64(i + 1)},
-		}
+		h := GenerateTestFloatHistogram(i)
 		if i > 0 {
 			h.CounterResetHint = histogram.NotCounterReset
 		}
-		r = append(r, &h)
+		r = append(r, h)
 	}
-
 	return r
 }
 
-func GenerateTestGaugeFloatHistograms(n int) (r []*histogram.FloatHistogram) {
-	for x := 0; x < n; x++ {
-		i := rand.Intn(n)
-		r = append(r, &histogram.FloatHistogram{
-			CounterResetHint: histogram.GaugeType,
+// Generates a test float histogram, it is up to the user to set any known counter reset hint.
+func GenerateTestFloatHistogram(i int) *histogram.FloatHistogram {
+	return &histogram.FloatHistogram{
 		Count:         10 + float64(i*8),
 		ZeroCount:     2 + float64(i),
 		ZeroThreshold: 0.001,
@@ -2138,8 +2112,18 @@ func GenerateTestGaugeFloatHistograms(n int) (r []*histogram.FloatHistogram) {
 			{Offset: 1, Length: 2},
 		},
 		NegativeBuckets: []float64{float64(i + 1), float64(i + 2), float64(i + 1), float64(i + 1)},
-		})
 	}
+}
 
+func GenerateTestGaugeFloatHistograms(n int) (r []*histogram.FloatHistogram) {
+	for x := 0; x < n; x++ {
+		r = append(r, GenerateTestGaugeFloatHistogram(rand.Intn(n)))
+	}
 	return r
 }
+
+func GenerateTestGaugeFloatHistogram(i int) *histogram.FloatHistogram {
+	h := GenerateTestFloatHistogram(i)
+	h.CounterResetHint = histogram.GaugeType
+	return h
+}