Ts all the tests (#1998)

* Convert tests to TypeScript

* Add types for tests

* Rename files to TS

* Fix up test imports

* Fix TSC errors

* Liiiint

* Add types to util method signatures

* Some more types

test-mocha/common/entity/timer_time_remaining_test.ts

@@ -0,0 +1,52 @@
+import { assert } from "chai";
+import * as sinon from "sinon";
+
+import timerTimeRemaining from "../../../src/common/entity/timer_time_remaining";
+
+describe("timerTimeRemaining", () => {
+  it("works with idle timers", () => {
+    assert.strictEqual(
+      timerTimeRemaining({
+        state: "idle",
+        attributes: {
+          remaining: "0:01:05",
+        },
+      } as any),
+      65
+    );
+  });
+
+  it("works with paused timers", () => {
+    assert.strictEqual(
+      timerTimeRemaining({
+        state: "paused",
+        attributes: {
+          remaining: "0:01:05",
+        },
+      } as any),
+      65
+    );
+  });
+
+  describe("active timers", () => {
+    let clock;
+    beforeEach(() => {
+      clock = sinon.useFakeTimers(new Date("2018-01-17T16:15:30Z"));
+    });
+    afterEach(() => {
+      clock.restore();
+    });
+    it("works", () => {
+      assert.strictEqual(
+        timerTimeRemaining({
+          state: "active",
+          attributes: {
+            remaining: "0:01:05",
+          },
+          last_changed: "2018-01-17T16:15:12Z",
+        } as any),
+        47
+      );
+    });
+  });
+});