Fixing evict() such that it handles a size of 0 and 1 properly

(redo) Fixing `evict()` such that it handles a size of 0 and 1 properly

Adding an empty eviction test

Minor tweak to new test

need more coffee

need more coffee part 2

lib/tiny-lru.cjs.js

@@ -50,13 +50,21 @@ class LRU {
 			return this;
 		}
 
-		evict () {
-			const item = this.first;
+		evict (bypass = false) {
+			if (bypass || this.size > 0) {
+				const item = this.first;
 
-			delete this.items[item.key];
-			this.first = item.next;
-			this.first.prev = null;
-			this.size--;
+				delete this.items[item.key];
+				this.size--;
+
+				if (this.size === 0) {
+					this.first = null;
+					this.last = null;
+				} else {
+					this.first = item.next;
+					this.first.prev = null;
+				}
+			}
 
 			return this;
 		}
@@ -112,7 +120,7 @@ class LRU {
 				}
 			} else {
 				if (this.max > 0 && this.size === this.max) {
-					this.evict();
+					this.evict(true);
 				}
 
 				item = this.items[key] = {

src/lru.js

@@ -48,13 +48,21 @@
 			return this;
 		}
 
-		evict () {
-			const item = this.first;
+		evict (bypass = false) {
+			if (bypass || this.size > 0) {
+				const item = this.first;
 
-			delete this.items[item.key];
-			this.first = item.next;
-			this.first.prev = null;
-			this.size--;
+				delete this.items[item.key];
+				this.size--;
+
+				if (this.size === 0) {
+					this.first = null;
+					this.last = null;
+				} else {
+					this.first = item.next;
+					this.first.prev = null;
+				}
+			}
 
 			return this;
 		}
@@ -110,7 +118,7 @@
 				}
 			} else {
 				if (this.max > 0 && this.size === this.max) {
-					this.evict();
+					this.evict(true);
 				}
 
 				item = this.items[key] = {

test/lru.js

@@ -71,20 +71,38 @@ exports.deletion = {
 
 exports.smallEvict = {
 	setUp: function (done) {
-		this.cache = lru(4);
-		this.items = ["a"];
+		this.cache = lru(1);
+		this.items = ["a", "b"];
 		done();
 	},
 	test: function (test) {
 		this.items.forEach(i => this.cache.set(i, false));
 		test.expect(6);
-		test.equal(this.cache.first.key, "a", "Should be 'a'");
-		test.equal(this.cache.last.key, "a", "Should be 'a'");
+		test.equal(this.cache.first.key, "b", "Should be 'b'");
+		test.equal(this.cache.last.key, "b", "Should be 'b'");
 		test.equal(this.cache.size, 1, "Should be '1'");
 		this.cache.evict();
-		test.equal(this.cache.first.key, null, "Should be 'null'");
-		test.equal(this.cache.last.key, null, "Should be 'null'");
+		test.equal(this.cache.first, null, "Should be 'null'");
+		test.equal(this.cache.last, null, "Should be 'null'");
 		test.equal(this.cache.size, 0, "Should be 'null'");
 		test.done();
 	}
 };
+
+exports.emptyEvict = {
+	setUp: function (done) {
+		this.cache = lru(1);
+		done();
+	},
+	test: function (test) {
+		test.expect(6);
+		test.equal(this.cache.first, null, "Should be 'null'");
+		test.equal(this.cache.last, null, "Should be 'null'");
+		test.equal(this.cache.size, 0, "Should be 'null'");
+		this.cache.evict();
+		test.equal(this.cache.first, null, "Should be 'null'");
+		test.equal(this.cache.last, null, "Should be 'null'");
+		test.equal(this.cache.size, 0, "Should be 'null'");
+		test.done();
+	}
+};