coding-practice/problems/3025-find-the-number-of-ways-to-place-people-i/go/main_test.go

// LeetCode 3025 Go 單元測試
package main

import (
    "math/rand"
    "testing"
	"fmt"
)

func TestCase1_ExampleFromProblem(t *testing.T) {
    // Arrange
	points := [][]int{
		{6, 2},
		{4, 4},
		{2, 6},
	}
	expected := 2

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase1 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestCase2_TwoPoints(t *testing.T) {
	// Arrange
    points := [][]int{
		{1, 3},
		{2, 1},
	}
	expected := 1

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase2 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestCase3_NoValidPairs(t *testing.T) {
	// Arrange - 沒有有效點對的情況
	points := [][]int{
		{1, 1},
		{2, 2},
		{3, 3},
	}
	expected := 0

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase3 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestCase4_SameXCoordinate(t *testing.T) {
	// Arrange - x 座標相同的情況
	points := [][]int{
		{3, 5}, // A
		{3, 2}, // B
		{3, 1}, // C
	}
	// 詳細分析:
	// (A, B): (3,5) -> (3,2) ✓ 矩形是線段，無其他點
	// (A, C): (3,5) -> (3,1) ✗ 點B在矩形內
	// (B, C): (3,2) -> (3,1) ✓ 矩形是線段，無其他點
	expected := 2

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase4 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestCase5_SameYCoordinate(t *testing.T) {
	// Arrange - y 座標相同的情況
	points := [][]int{
		{1, 4}, // A
		{3, 4}, // B
		{5, 4}, // C
	}
	// 詳細分析:
	// (A, B): (1,4) -> (3,4) ✓ 矩形是線段，無其他點
	// (A, C): (1,4) -> (5,4) ✗ 點B在矩形內
	// (B, C): (3,4) -> (5,4) ✓ 矩形是線段，無其他點
	expected := 2

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase5 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestCase6_PointsInsideRectangle(t *testing.T) {
	// Arrange - 矩形內有其他點的情況
	points := [][]int{
		{0, 4}, // A
		{4, 0}, // B
		{2, 2}, // C
	}
	// 詳細分析:
	// (A, B): (0,4) -> (4,0) ✗ 點C在矩形內
	// (A, C): (0,4) -> (2,2) ✓ 點B不在矩形內
	// (C, B): (2,2) -> (4,0) ✓ 點A不在矩形內
	expected := 2

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase6 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestCase7_PointsOnBorder(t *testing.T) {
	// Arrange - 點在矩形邊界上的情況
	points := [][]int{
		{0, 3}, // A
		{3, 0}, // B
		{0, 0}, // C
	}
	// 詳細分析:
	// (A, B): (0,3) -> (3,0) ✗ 點C在矩形邊界上
	// (A, C): (0,3) -> (0,0) ✓ 矩形是線段，點B不在其中
	// (C, B): (0,0) -> (3,0) ✓ 矩形是線段，點A不在其中
	expected := 2

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestCase7 failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestEdgeCases_MinimumPoints(t *testing.T) {
	// Arrange - 最少點數情況 (題目限制 n >= 2)
	points := [][]int{
		{0, 1},
		{1, 0},
	}
	expected := 1 // (0,1) 在 (1,0) 的左上方

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestEdgeCases_MinimumPoints failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestEdgeCases_MaxCoordinateValues(t *testing.T) {
	// Arrange - 最大座標值情況 (題目限制 0 <= coordinates <= 50)
	points := [][]int{
		{0, 50},  // A
		{50, 0},  // B
		{25, 25}, // C
	}
	expected := 2 // (A,C) 和 (C,B) 有效

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestEdgeCases_MaxCoordinateValues failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestEdgeCases_EmptyArray(t *testing.T) {
	// Arrange - 空陣列情況
	points := [][]int{}
	expected := 0

	// Act
	result := numberOfPairs(points)

	// Assert
	if result != expected {
		t.Errorf("TestEdgeCases_EmptyArray failed. Expected: %v, Got: %v", expected, result)
	}
}

func TestEdgeCases_MaxPoints_RandomPattern(t *testing.T) {
	// Arrange - 50個不同的點，隨機模式
	points := make([][]int, 0, 50)
	usedPoints := make(map[string]bool)
	
	// 使用固定種子確保測試可重現
	rand.Seed(42)

	for len(points) < 50 {
		x := rand.Intn(51) // 0-50
		y := rand.Intn(51) // 0-50
		pointKey := fmt.Sprintf("%d,%d", x, y)

		if !usedPoints[pointKey] {
			usedPoints[pointKey] = true
			points = append(points, []int{x, y})
		}
	}

	// Act
	result := numberOfPairs(points)

	// Assert
	if result < 0 {
		t.Errorf("TestEdgeCases_MaxPoints_RandomPattern failed. Result should be non-negative, got: %v", result)
	}
	if result > 50*49 {
		t.Errorf("TestEdgeCases_MaxPoints_RandomPattern failed. Result should not exceed 50*49, got: %v", result)
	}

	// 額外驗證：確保所有點都是不同的
	distinctPoints := make(map[string]bool)
	for _, point := range points {
		key := fmt.Sprintf("%d,%d", point[0], point[1])
		distinctPoints[key] = true
	}
	if len(distinctPoints) != 50 {
		t.Errorf("TestEdgeCases_MaxPoints_RandomPattern failed. Expected 50 distinct points, got: %v", len(distinctPoints))
	}
}