refactor: edge and rectangle in separate packages

cmd/09/edge/edge_test.go

@@ -0,0 +1,71 @@
+package edge_test
+
+import (
+	"testing"
+
+	"github.com/StevanFreeborn/advent-of-code-2025/cmd/09/edge"
+	"github.com/StevanFreeborn/advent-of-code-2025/internal/position"
+)
+
+func TestFrom(t *testing.T) {
+	start := position.From(1, 2)
+	end := position.From(3, 4)
+
+	e := edge.From(start, end)
+
+	if e.Start() != start {
+		t.Errorf("Expected start position %v, got %v", start, e.Start())
+	}
+
+	if e.End() != end {
+		t.Errorf("Expected end position %v, got %v", end, e.End())
+	}
+}
+
+func TestVerticallyContains(t *testing.T) {
+	start := position.From(1, 2)
+	end := position.From(3, 4)
+	e := edge.From(start, end)
+
+	tests := []struct {
+		p        position.Position
+		expected bool
+	}{
+		{position.From(2, 3), true},
+		{position.From(1, 2), true},
+		{position.From(3, 4), true},
+		{position.From(0, 0), false},
+		{position.From(4, 5), false},
+	}
+
+	for _, test := range tests {
+		result := e.VerticallyContains(test.p)
+
+		if result != test.expected {
+			t.Errorf("VerticallyContains(%v) = %v; want %v", test.p, result, test.expected)
+		}
+	}
+}
+
+func TestIntersectsHorizontalLineAt(t *testing.T) {
+	start := position.From(1, 2)
+	end := position.From(3, 4)
+	e := edge.From(start, end)
+
+	tests := []struct {
+		p        position.Position
+		expected bool
+	}{
+		{position.From(2, 3), true},
+		{position.From(1, 2), true},
+		{position.From(3, 4), true},
+	}
+
+	for _, test := range tests {
+		result := e.IntersectsHorizontalLineAt(test.p)
+
+		if result != test.expected {
+			t.Errorf("IntersectsHorizontalLineAt(%v) = %v; want %v", test.p, result, test.expected)
+		}
+	}
+}