feat: Turtle tests ( Fixes #25 )

Author: James Brundage

Turtle.tests.ps1

@@ -0,0 +1,16 @@
+describe Turtle {
+    it "Draws things with simple commands" {
+        $null = $turtle.Clear().Square()
+        $turtleSquaredPoints = $turtle.Points       
+        $turtleSquaredPoints.Length | Should -Be 8
+        $turtleSquaredPoints | 
+            Measure-Object -Sum | 
+            Select-Object -ExpandProperty Sum | 
+            Should -Be 0
+    } 
+
+    it 'Can draw an L-system, like a Sierpinski triangle' {
+        $turtle.Clear().SierpinskiTriangle(200, 2, 120).points.Count |
+            Should -Be 54
+    }
+}