From af85b577f139469f53723f2a5efe7a43562a52ee Mon Sep 17 00:00:00 2001
From: Kir_Antipov <kp.antipov@gmail.com>
Date: Fri, 30 Dec 2022 03:17:55 +0000
Subject: [PATCH] Made an interface for all key-value iterables out there

---
 src/utils/collections/key-value-iterable.ts   | 24 +++++++++++++++++++
 .../collections/key-value-iterable.spec.ts    | 20 ++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 src/utils/collections/key-value-iterable.ts
 create mode 100644 tests/unit/utils/collections/key-value-iterable.spec.ts

diff --git a/src/utils/collections/key-value-iterable.ts b/src/utils/collections/key-value-iterable.ts
new file mode 100644
index 0000000..56250f7
--- /dev/null
+++ b/src/utils/collections/key-value-iterable.ts
@@ -0,0 +1,24 @@
+/**
+ * Represents an object that contains key-value pairs and exposes an `entries()` method
+ * to iterate over those pairs.
+ */
+export interface KeyValueIterable<K, V> {
+    /**
+     * Returns an iterable containing the key-value pairs of the object.
+     */
+    entries(): Iterable<[K, V]>;
+}
+
+/**
+ * Type guard to check if the given object implements the {@link KeyValueIterable} interface.
+ *
+ * @template K - The key type.
+ * @template V - The value type.
+ *
+ * @param obj - The object to check.
+ *
+ * @returns `true` if the object implements the {@link KeyValueIterable} interface; otherwise, `false`.
+ */
+export function isKeyValueIterable<K, V>(obj: unknown): obj is KeyValueIterable<K, V> {
+    return typeof (obj as KeyValueIterable<K, V>)?.entries === "function";
+}
diff --git a/tests/unit/utils/collections/key-value-iterable.spec.ts b/tests/unit/utils/collections/key-value-iterable.spec.ts
new file mode 100644
index 0000000..5ece133
--- /dev/null
+++ b/tests/unit/utils/collections/key-value-iterable.spec.ts
@@ -0,0 +1,20 @@
+import { isKeyValueIterable } from "@/utils/collections/key-value-iterable";
+
+describe("isKeyValueIterable", () => {
+    test("returns true for objects that have entries", () => {
+        expect(isKeyValueIterable(new Map())).toBe(true);
+        expect(isKeyValueIterable(new Set())).toBe(true);
+        expect(isKeyValueIterable([])).toBe(true);
+        expect(isKeyValueIterable({ entries: () => [] })).toBe(true);
+    });
+
+    test("returns false for objects that has no entries", () => {
+        expect(isKeyValueIterable({})).toBe(false);
+        expect(isKeyValueIterable(new Date())).toBe(false);
+    });
+
+    test("returns false for null and undefined", () => {
+        expect(isKeyValueIterable(null)).toBe(false);
+        expect(isKeyValueIterable(undefined)).toBe(false);
+    });
+});