feature: added return of removed element when queue is full

hbarcelos · Feb 5, 2020 · 96d9680 · 96d9680
1 parent ea68789
commit 96d9680
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Showing 2 changed files with 24 additions and 0 deletions.
diff --git a/round-linked-queue.js b/round-linked-queue.js
@@ -30,6 +30,8 @@ class RoundLinkedQueue {
       next: null,
     };
 
+    let removedElement;
+
     if (this.length < this.maxLength) {
       if (!this._first) {
         this._first = node;
@@ -38,11 +40,14 @@ class RoundLinkedQueue {
 
       this._length += 1;
     } else {
+      removedElement = this._first.data;
       this._first = this._first.next;
     }
 
     this._last.next = node;
     this._last = node;
+
+    return removedElement;
   }
 }
 

diff --git a/round-linked-queue.test.js b/round-linked-queue.test.js
@@ -70,5 +70,24 @@ describe("Round-Queue", () => {
       // Length should still be the same
       expect(queue.length).to.equal(3, "length not properly set");
     });
+
+    it("Should return the removed element from a full queue", () => {
+      const queue = new RoundQueue(3);
+      queue.add(1);
+      queue.add(2);
+      queue.add(3);
+
+      const result = queue.add(4);
+
+      expect(result).to.equal(1, "removed wrong element");
+    });
+
+    it("Should return undefined when the queue is not full", () => {
+      const queue = new RoundQueue(3);
+
+      const result = queue.add(1);
+
+      expect(result).to.equal(undefined, "should not return an element");
+    });
   });
 });