Implement unit tests for the getRotationMatrix core utility function

This function is mostly covered indirectly by higher-level tests, but
unlike the other core utility functions it lacked dedicated unit tests.
This commit implements unit tests for it that also cover the previously
uncovered exception case, which brings coverage of the function to 100%
and ever so slighly increases coverage of the overarching file.

Author: timvandermeij

test/unit/core_utils_spec.js

@@ -21,6 +21,7 @@ import {
   escapeString,
   getInheritableProperty,
   getModificationDate,
+  getRotationMatrix,
   getSizeInBytes,
   isWhiteSpace,
   numberToString,
@@ -566,6 +567,20 @@ describe("core_utils", function () {
     });
   });
 
+  fdescribe("getRotationMatrix", function () {
+    it("should get a rotation matrix for valid rotation values", function () {
+      expect(getRotationMatrix(90, 10, 20)).toEqual([0, 1, -1, 0, 10, 0]);
+      expect(getRotationMatrix(180, 10, 20)).toEqual([-1, 0, 0, -1, 10, 20]);
+      expect(getRotationMatrix(270, 10, 20)).toEqual([0, -1, 1, 0, 0, 20]);
+    });
+
+    it("throws an exception for invalid rotation values", function () {
+      expect(() => getRotationMatrix(42, 10, 20)).toThrow(
+        new Error("Invalid rotation")
+      );
+    });
+  });
+
   describe("getSizeInBytes", function () {
     it("should get the size in bytes to use to represent a positive integer", function () {
       expect(getSizeInBytes(0)).toEqual(0);