testcase for remove_collinear_points in Polygon

src/CMakeLists.txt

@@ -306,6 +306,7 @@ set(SLIC3R_TEST_SOURCES
     ${TESTDIR}/libslic3r/test_geometry.cpp
     ${TESTDIR}/libslic3r/test_log.cpp
     ${TESTDIR}/libslic3r/test_model.cpp
+    ${TESTDIR}/libslic3r/test_polygon.cpp
     ${TESTDIR}/libslic3r/test_print.cpp
     ${TESTDIR}/libslic3r/test_printgcode.cpp
     ${TESTDIR}/libslic3r/test_skirt_brim.cpp

src/test/libslic3r/test_polygon.cpp

@@ -0,0 +1,48 @@
+
+#include <catch.hpp>
+
+#include "Point.hpp"
+#include "Polygon.hpp"
+
+
+using namespace Slic3r;
+
+
+// This test currently only covers remove_collinear_points.
+// All remaining tests are to be ported from xs/t/06_polygon.t
+
+Points collinear_circle({
+    Point::new_scale(0, 0), // 3 collinear points at beginning
+    Point::new_scale(10, 0),
+    Point::new_scale(20, 0),
+    Point::new_scale(30, 10),
+    Point::new_scale(40, 20), // 2 collinear points
+    Point::new_scale(40, 30),
+    Point::new_scale(30, 40), // 3 collinear points
+    Point::new_scale(20, 40),
+    Point::new_scale(10, 40),
+    Point::new_scale(-10, 20),
+    Point::new_scale(-20, 10),
+    Point::new_scale(-20, 0), // 3 collinear points at end
+    Point::new_scale(-10, 0),
+    Point::new_scale(-5, 0)
+});
+
+
+SCENARIO("Remove collinear points from Polygon") {
+    GIVEN("Polygon with collinear points"){
+        Polygon p(collinear_circle);
+        WHEN("collinear points are removed") {
+            p.remove_collinear_points();
+            THEN("Leading collinear points are removed") {
+                REQUIRE(p.points.front() == Point::new_scale(20, 0));
+            }
+            THEN("Trailing collinear points are removed") {
+                REQUIRE(p.points.back() == Point::new_scale(-20, 0));
+            }
+            THEN("Number of remaining points is correct") {
+                REQUIRE(p.points.size() == 7);
+            }
+        }
+    }
+}