Add tests for 'EventEmitter' module;

Author: austindd

test/__tests__/EventEmitter_test.re

@@ -0,0 +1,122 @@
+open Jest;
+
+describe("EventEmitter", () => {
+  test(
+    "'Emitter.make' should create a new emitter instance that is defined", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let emitter = Emitter1.make();
+    expect(emitter->Js.Undefined.return) |> toBeDefined;
+  });
+
+  test("'Emitter.addListener' should add a new event listener", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let listeners =
+      Emitter1.(
+        {
+          make()->addListener(Events.text, _ => ())->listeners(Events.text);
+        }
+      );
+    expect(Array.length(listeners)) |> toBe(1);
+  });
+
+  test("'Emitter.on' should add a new event listener", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let listeners =
+      Emitter1.(
+        {
+          make()->on(Events.text, _ => ())->listeners(Events.text);
+        }
+      );
+    expect(Array.length(listeners)) |> toBe(1);
+  });
+
+  test("'Emitter.on' should add a new event listener", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let listeners =
+      Emitter1.(
+        {
+          make()->on(Events.text, _ => ())->listeners(Events.text);
+        }
+      );
+    expect(Array.length(listeners)) |> toBe(1);
+  });
+
+  test("'Emitter.removeListener' should remove the event listener", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let eventListener = (_) => ();
+    let listeners =
+      Emitter1.(
+        {
+          make()
+            |> on(_, Events.text, eventListener)
+            |> removeListener(_, Events.text, eventListener)
+            |> listeners(_, Events.text);
+        }
+      );
+    expect(Array.length(listeners)) |> toBe(0);
+  });
+
+  test("'Emitter.off' should remove the event listener", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let eventListener = (_) => ();
+    let listeners =
+      Emitter1.(
+        {
+          make()
+            |> on(_, Events.text, eventListener)
+            |> off(_, Events.text, eventListener)
+            |> listeners(_, Events.text);
+        }
+      );
+    expect(Array.length(listeners)) |> toBe(0);
+  });
+
+  test("'Emitter.emit' should execute each listener for the correct event", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let ref1 = ref(0);
+    let ref2 = ref(0);
+    let data1 = 1;
+    let data2 = 2;
+    let listener1 = (_) => { ref1 := data1; };
+    let listener2 = (_) => { ref2 := data2; };
+    Emitter1.({
+        let emitter =
+          make()
+          |> on(_, Events.integer, listener1)
+          |> on(_, Events.integer, listener2);
+          emit(emitter, Events.integer, data1)->ignore;
+          emit(emitter, Events.integer, data2)->ignore;
+    });
+    Assert.strictEqual(ref1^, 1);
+    Assert.strictEqual(ref2^, 2);
+    expect(ref1^ === 1 && ref2^ === 2) |> toBe(true);
+  });
+
+  test("'Emitter.removeAllListeners' should remove all event listeners", () => {
+    open! ExpectJs;
+    open! EventEmitterTestLib;
+    let eventListener = (_) => ();
+    let emitter =
+      Emitter1.(
+        {
+          make()
+            |> on(_, Events.text, eventListener)
+            |> on(_, Events.text, eventListener)
+            |> on(_, Events.text, eventListener)
+        }
+      );
+    // Make sure 3 listeners were indeed added:
+    Assert.strictEqual(Emitter1.(listeners(emitter, Events.text))->Array.length, 3);
+    // Remove all the listeners:
+    Emitter1.removeAllListeners(emitter)->ignore;
+    expect(Emitter1.(listeners(emitter, Events.text))->Array.length) |> toBe(0);
+  });
+
+});

test/test_lib/EventEmitterTestLib.re

@@ -0,0 +1,14 @@
+module Emitter1 = {
+  include EventEmitter.Make();
+
+  let uniqueSymbol: Js.Types.symbol = [%raw {|Symbol("emitter1")|}];
+
+  module Events = {
+    let symbol: Event.t(Js.Types.symbol => unit, t) = Event.fromSymbol(uniqueSymbol);
+    let text: Event.t(string => unit, t) = Event.fromString("text");
+    let integer: Event.t(int => unit, t) = Event.fromString("integer");
+    let textAndInteger: Event.t((string, int) => unit, t) = Event.fromString("textAndInteger");
+  };
+
+};
+