Added unit tests

statistics/primitives_test.go

@@ -0,0 +1,123 @@
+package statistics
+
+import (
+	"math"
+	"testing"
+)
+
+type TestEntry struct {
+	Name     string
+	Input    []float64
+	Expected float64
+}
+
+func cmpVal(x, y float64) bool {
+	const epsilon = 1e-9
+
+	return math.Abs(x-y) < epsilon
+}
+
+func TestMean(t *testing.T) {
+	tests := []TestEntry{
+		{"Empty list", []float64{}, 0},
+		{"Single element", []float64{5.0}, 5.0},
+		{"Multiple elements", []float64{2.3, 6.4, -2.2, 8.4}, 3.725},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			got := Mean(test.Input)
+			if !cmpVal(got, test.Expected) {
+				t.Errorf("Got %v, wanted %v", got, test.Expected)
+			}
+		})
+	}
+}
+
+func TestStdDev(t *testing.T) {
+	tests := []TestEntry{
+		{"Empty list", []float64{}, 0},
+		{"Single element", []float64{5.0}, 0},
+		{"Multiple elements", []float64{5.0, -4.2, 3.4, 7.2}, 4.288064831599448},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			got := StdDev(test.Input)
+			if !cmpVal(got, test.Expected) {
+				t.Errorf("Got %v, wanted %v", got, test.Expected)
+			}
+		})
+	}
+}
+
+func TestMedian(t *testing.T) {
+	tests := []TestEntry{
+		{"Empty list", []float64{}, 0},
+		{"Single element", []float64{5.0}, 5.0},
+		{"Multiple elements (even)", []float64{5.0, -4.2, 3.4, 7.2}, 4.2},
+		{"Multiple elements (odd)", []float64{5.0, -4.2, 1.4, 3.4, 7.2}, 3.4},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			got := Median(test.Input)
+			if !cmpVal(got, test.Expected) {
+				t.Errorf("Got %v, wanted %v", got, test.Expected)
+			}
+		})
+	}
+}
+
+func TestMode(t *testing.T) {
+	tests := []TestEntry{
+		{"Empty list", []float64{}, 0},
+		{"Single element", []float64{5.0}, 5.0},
+		{"Unique modes", []float64{1.0, 2.0, 2.0, 3.0}, 2.0},
+		{"Multi-modal", []float64{1.0, 1.0, 2.0, 3.0, 3.0}, 3.0},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			got := Mode(test.Input)
+			if !cmpVal(got, test.Expected) {
+				t.Errorf("Got %v, wanted %v", got, test.Expected)
+			}
+		})
+	}
+}
+
+func TestRobustZScore(t *testing.T) {
+	// Gaussian distributed dataset representing "normal"
+	// temperatures; that is, without anomalies
+	normalTemps := []float64{
+		18.0, 19.0, 19.0, 20.0, 20.0,
+		20.0, 21.0, 21.0, 21.0, 21.0,
+		22.0, 22.0, 22.0, 22.0, 22.0,
+		23.0, 23.0, 23.0, 24.0, 24.0,
+	}
+
+	tests := []TestEntry{
+		{"Empty list", []float64{}, 0},
+		{"Single element", []float64{20.0}, 0},
+		{"Temperatures without anomalies", normalTemps, 0},
+		{"High anomaly", append(normalTemps, 30.0), 30.0},
+		{"Low anomaly", append(normalTemps, 5.0), 5.0},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			got := RobustZScore(test.Input)
+
+			if len(got) != 0 {
+				if !cmpVal(got[0].Value, test.Expected) {
+					t.Errorf("Got %v, wanted %v", got, test.Expected)
+				}
+			} else {
+				if test.Expected != 0 {
+					t.Errorf("Got [], wanted %v", test.Expected)
+				}
+			}
+		})
+	}
+}