test: add pimath unit tests

Author: elgopher

pimath/pimath_test.go

@@ -0,0 +1,96 @@
+// Copyright 2025 Jacek Olszak
+// This code is licensed under MIT license (see LICENSE for details)
+
+package pimath_test
+
+import (
+	"testing"
+
+	"github.com/elgopher/pi/pimath"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestClamp(t *testing.T) {
+	tests := map[string]struct {
+		x, min, max int
+		expected    int
+	}{
+		"lower than min": {
+			x: -1, min: 0, max: 1,
+			expected: 0,
+		},
+		"equal to min": {
+			x: 0, min: 0, max: 1,
+			expected: 0,
+		},
+		"greater than max": {
+			x: 2, min: 0, max: 1,
+			expected: 1,
+		},
+		"equal to max": {
+			x: 1, min: 0, max: 1,
+			expected: 1,
+		},
+		"between min and max": {
+			x: 1, min: 0, max: 2,
+			expected: 1,
+		},
+	}
+	for testName, testCase := range tests {
+		t.Run(testName, func(t *testing.T) {
+			actual := pimath.Clamp(testCase.x, testCase.min, testCase.max)
+			assert.Equal(t, testCase.expected, actual)
+		})
+	}
+}
+
+func TestLerp(t *testing.T) {
+	tests := map[string]struct {
+		a, b, t  float64
+		expected float64
+	}{
+		"in the middle": {
+			a: 1, b: 2, t: 0.5,
+			expected: 1.5,
+		},
+		"beginning": {
+			a: 1, b: 2, t: 0,
+			expected: 1,
+		},
+		"end": {
+			a: 1, b: 2, t: 1,
+			expected: 2,
+		},
+	}
+	for testName, testCase := range tests {
+		t.Run(testName, func(t *testing.T) {
+			actual := pimath.Lerp(testCase.a, testCase.b, testCase.t)
+			assert.InDelta(t, testCase.expected, actual, 0.01)
+		})
+	}
+}
+
+func TestDistance(t *testing.T) {
+	tests := map[string]struct {
+		x1, y1   float64
+		x2, y2   float64
+		expected float64
+	}{
+		"(0,0) to (2,2)": {
+			x1: 0, y1: 0,
+			x2: 2, y2: 2,
+			expected: 2.83,
+		},
+		"(2,2) to (0,0)": {
+			x1: 2, y1: 2,
+			x2: 0, y2: 0,
+			expected: 2.83,
+		},
+	}
+	for testName, testCase := range tests {
+		t.Run(testName, func(t *testing.T) {
+			actual := pimath.Distance(testCase.x1, testCase.y1, testCase.x2, testCase.y2)
+			assert.InDelta(t, testCase.expected, actual, 0.01)
+		})
+	}
+}