test: improve create_out_transition tests

test/transitions/index.ts

@@ -9,7 +9,7 @@ describe('transitions', () => {
 
 	before(() => {
 		originalRequestAnimationFrame = global.requestAnimationFrame;
-    global.requestAnimationFrame = cb => cb();
+		global.requestAnimationFrame = (cb) => cb();
 	});
 
 	after(() => {
@@ -21,18 +21,14 @@ describe('transitions', () => {
 	});
 
 	describe('create_out_transition', () => {
-		describe('when then transition function returns undefined', () => {
+		describe('when then transition function does not return a tick function', () => {
 			describe('when calling the end function with reset param equals to true', () => {
 				it('should not throw an exception', () => {
+					const noTickConfigs: TransitionConfig[] = [undefined, null, {}];
+
+					noTickConfigs.forEach((config) => {
 						const node = document.createElement('div');
-					const transitionConfig: TransitionConfig = {
+						const { end } = create_out_transition(node, () => config, {});
-						duration: 0
-					};
-					const { end } = create_out_transition(
-						node,
-						() => undefined,
-						transitionConfig
-					);
 						let error: Error | null = null;
 
 						try {
@@ -46,4 +42,27 @@ describe('transitions', () => {
 				});
 			});
 		});
+
+		describe('when the transition function returns a config object with defined tick function', () => {
+			describe('when calling the end function with reset param equals to true', () => {
+				it('should call the tick function', () => {
+					const node = document.createElement('div');
+					let tick = 0;
+					const transitionConfig: TransitionConfig = {
+						duration: 0,
+						tick: () => (tick += 1)
+					};
+					const { end } = create_out_transition(
+						node,
+						() => transitionConfig,
+						{}
+					);
+
+					end(true);
+
+					assert.equal(tick, 1);
+				});
+			});
+		});
+	});
 });