Add GridCache tests

src/renderer/GridCache.test.ts

@@ -0,0 +1,61 @@
+/**
+ * @license MIT
+ */
+
+import { assert } from 'chai';
+import { GridCache } from './GridCache';
+
+describe('GridCache', () => {
+  let grid: GridCache<number>;
+
+  beforeEach(() => {
+    grid = new GridCache<number>();
+  });
+
+  describe('constructor', () => {
+    it('should create an empty cache', () => {
+      assert.equal(grid.cache.length, 0);
+    });
+  });
+
+  describe('resize', () => {
+    it('should fill all new elements with null', () => {
+      grid.resize(2, 2);
+      assert.equal(grid.cache.length, 2);
+      assert.equal(grid.cache[0].length, 2);
+      assert.equal(grid.cache[0][0], null);
+      assert.equal(grid.cache[0][1], null);
+      assert.equal(grid.cache[1].length, 2);
+      assert.equal(grid.cache[1][0], null);
+      assert.equal(grid.cache[1][1], null);
+      grid.resize(3, 2);
+      assert.equal(grid.cache.length, 3);
+      assert.equal(grid.cache[2][0], null);
+      assert.equal(grid.cache[2][1], null);
+    });
+
+    it('should remove rows/cols from the cache when reduced', () => {
+      grid.resize(2, 2);
+      grid.resize(1, 1);
+      assert.equal(grid.cache.length, 1);
+      assert.equal(grid.cache[0].length, 1);
+    });
+
+    it('should not touch existing cache entries if they fit in the new cache', () => {
+      grid.resize(1, 1);
+      assert.equal(grid.cache[0][0], null);
+      grid.cache[0][0] = 1;
+      grid.resize(2, 1);
+      assert.equal(grid.cache[0][0], 1);
+    });
+  });
+
+  describe('clear', () => {
+    it('should make all entries null', () => {
+      grid.resize(1, 1);
+      grid.cache[0][0] = 1;
+      grid.clear();
+      assert.equal(grid.cache[0][0], null);
+    });
+  });
+});