shapes: add rectangle perimeter and area funcs

shapes/shapes.go

@@ -0,0 +1,9 @@
+package shapes
+
+func Perimeter(width, height float64) float64 {
+	return 2 * (width + height)
+}
+
+func Area(width, height float64) float64 {
+	return width * height
+}

shapes/shapes_test.go

@@ -0,0 +1,21 @@
+package shapes
+
+import "testing"
+
+func TestPerimeter(t *testing.T) {
+	got := Perimeter(30.5, 20.5)
+	exp := 102.0
+
+	if got != exp {
+		t.Errorf("got %.2f expected %.2f", got, exp)
+	}
+}
+
+func TestArea(t *testing.T) {
+	got := Area(30.5, 20.5)
+	exp := 625.25
+
+	if got != exp {
+		t.Errorf("got %.2f expected %.2f", got, exp)
+	}
+}