sparkline values cleanup enhancements and test

component/sparkline/sparkline.go

@@ -77,9 +77,14 @@ func (s *SparkLine) consumeSample(sample *data.Sample) {
 	s.maxValue = max
 	s.minValue = min
 
-	// perform cleanup once in a while
 	if len(s.values)%100 == 0 {
-		s.values = append(s.values[:0], s.values[len(s.values)-s.Dx()+1:]...)
+		s.cleanup(s.Dx())
+	}
+}
+
+func (s *SparkLine) cleanup(maxSize int) {
+	if maxSize < len(s.values) {
+		s.values = append(s.values[:0], s.values[len(s.values)-maxSize:]...)
 	}
 }
 

component/sparkline/sparkline_test.go

@@ -0,0 +1,31 @@
+package sparkline
+
+import (
+	"testing"
+)
+
+func TestSparkLine_cleanup(t *testing.T) {
+	type Sparkline struct {
+		maxSize      int
+		expectedSize int
+		values       []float64
+	}
+	tests := []struct {
+		name      string
+		sparkline Sparkline
+	}{
+		{"should cleanup values to the max size", Sparkline{maxSize: 5, expectedSize: 5, values: []float64{1, 2, 3, 4, 5, 6, 7, 8}}},
+		{"should not cleanup values if max size is bigger than values len", Sparkline{maxSize: 5, expectedSize: 3, values: []float64{1, 2, 3}}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := &SparkLine{
+				values: tt.sparkline.values,
+			}
+			s.cleanup(tt.sparkline.maxSize)
+			if len(s.values) != tt.sparkline.expectedSize {
+				t.Errorf("Values size after cleanup is %v, but needed to be %v", len(s.values), tt.sparkline.expectedSize)
+			}
+		})
+	}
+}