Prometheus: Add Exemplar sampling for streaming parser (#56049) (#56571)

(cherry picked from commit 152c7f149a)

Co-authored-by: Todd Treece <360020+toddtreece@users.noreply.github.com>

pkg/tsdb/prometheus/querydata/framing_test.go

@@ -23,15 +23,15 @@ import (
 
 var update = true
 
-func TestMatrixResponses(t *testing.T) {
+func TestRangeResponses(t *testing.T) {
 	tt := []struct {
 		name     string
 		filepath string
 	}{
 		{name: "parse a simple matrix response", filepath: "range_simple"},
 		{name: "parse a simple matrix response with value missing steps", filepath: "range_missing"},
-		{name: "parse a response with Infinity", filepath: "range_infinity"},
-		{name: "parse a response with NaN", filepath: "range_nan"},
+		{name: "parse a matrix response with Infinity", filepath: "range_infinity"},
+		{name: "parse a matrix response with NaN", filepath: "range_nan"},
 		{name: "parse a response with legendFormat __auto", filepath: "range_auto"},
 	}
 
@@ -47,6 +47,26 @@ func TestMatrixResponses(t *testing.T) {
 	}
 }
 
+func TestExemplarResponses(t *testing.T) {
+	tt := []struct {
+		name     string
+		filepath string
+	}{
+		{name: "parse an exemplar response", filepath: "exemplar"},
+	}
+
+	for _, test := range tt {
+		enableWideSeries := false
+		queryFileName := filepath.Join("../testdata", test.filepath+".query.json")
+		responseFileName := filepath.Join("../testdata", test.filepath+".result.json")
+		goldenFileName := test.filepath + ".result.golden"
+		t.Run(test.name, goldenScenario(test.name, queryFileName, responseFileName, goldenFileName, enableWideSeries))
+		enableWideSeries = true
+		goldenFileName = test.filepath + ".result.streaming-wide.golden"
+		t.Run(test.name, goldenScenario(test.name, queryFileName, responseFileName, goldenFileName, enableWideSeries))
+	}
+}
+
 func goldenScenario(name, queryFileName, responseFileName, goldenFileName string, wide bool) func(t *testing.T) {
 	return func(t *testing.T) {
 		query, err := loadStoredQuery(queryFileName)
@@ -72,13 +92,14 @@ func goldenScenario(name, queryFileName, responseFileName, goldenFileName string
 // struct here, because it has `time.time` and `time.duration` fields that
 // cannot be unmarshalled from JSON automatically.
 type storedPrometheusQuery struct {
-	RefId        string
-	RangeQuery   bool
-	Start        int64
-	End          int64
-	Step         int64
-	Expr         string
-	LegendFormat string
+	RefId         string
+	RangeQuery    bool
+	ExemplarQuery bool
+	Start         int64
+	End           int64
+	Step          int64
+	Expr          string
+	LegendFormat  string
 }
 
 func loadStoredQuery(fileName string) (*backend.QueryDataRequest, error) {
@@ -96,11 +117,12 @@ func loadStoredQuery(fileName string) (*backend.QueryDataRequest, error) {
 	}
 
 	qm := models.QueryModel{
-		RangeQuery:   sq.RangeQuery,
-		Expr:         sq.Expr,
-		Interval:     fmt.Sprintf("%ds", sq.Step),
-		IntervalMS:   sq.Step * 1000,
-		LegendFormat: sq.LegendFormat,
+		RangeQuery:    sq.RangeQuery,
+		ExemplarQuery: sq.ExemplarQuery,
+		Expr:          sq.Expr,
+		Interval:      fmt.Sprintf("%ds", sq.Step),
+		IntervalMS:    sq.Step * 1000,
+		LegendFormat:  sq.LegendFormat,
 	}
 
 	data, err := json.Marshal(&qm)