feat(aigle): add value and reason functions

lib/aigle.js

@@ -128,6 +128,20 @@ class Aigle extends AigleCore {
     return this._value instanceof CancellationError;
   }
 
+  /**
+   * @return {*}
+   */
+  value() {
+    return this._resolved === 1 ? this._value : undefined;
+  }
+
+  /**
+   * @return {*}
+   */
+  reason() {
+    return this._resolved === 2 ? this._value : undefined;
+  }
+
   /**
    * @example
    * const { CancellationError } = Aigle;

test/lib/test.promise.js

@@ -811,3 +811,45 @@ parallel('#isCancelled', () => {
     assert.strictEqual(promise.isCancelled(), false);
   });
 });
+
+parallel('#value', () => {
+
+  it('should return a value if a promise is fulfilled', () => {
+
+    const value = Aigle.resolve(1).value();
+    assert.strictEqual(value, 1);
+  });
+
+  it('should not return a value if a promise is pending', () => {
+
+    const value = new Aigle(() => {}).value();
+    assert.strictEqual(value, undefined);
+  });
+
+  it('should not return a value if a promise is rejected', () => {
+
+    const value = Aigle.reject(1).value();
+    assert.strictEqual(value, undefined);
+  });
+});
+
+parallel('#reason', () => {
+
+  it('should return a reason if a promise is fulfilled', () => {
+
+    const reason = Aigle.resolve(1).reason();
+    assert.strictEqual(reason, undefined);
+  });
+
+  it('should not return a reason if a promise is pending', () => {
+
+    const reason = new Aigle(() => {}).reason();
+    assert.strictEqual(reason, undefined);
+  });
+
+  it('should not return a reason if a promise is rejected', () => {
+
+    const reason = Aigle.reject(1).reason();
+    assert.strictEqual(reason, 1);
+  });
+});