From 73e00624abc5c79a056f90bd7cdeeac178b3ab28 Mon Sep 17 00:00:00 2001
From: "Andres G. Aragoneses" <knocte@gmail.com>
Date: Tue, 10 Sep 2024 00:46:28 +0800
Subject: [PATCH] WIP1-4

---
 commitlint/fpHelpers.ts         |  3 +++
 commitlint/tests/testHelpers.ts | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/commitlint/fpHelpers.ts b/commitlint/fpHelpers.ts
index 5af094d2..477cc350 100644
--- a/commitlint/fpHelpers.ts
+++ b/commitlint/fpHelpers.ts
@@ -53,6 +53,9 @@ export class OptionStatic {
 export class TypeHelpers {
     // because instanceof doesn't work with primitive types (e.g. String), taken from https://stackoverflow.com/a/58184883/544947
     public static IsInstanceOf(variable: any, type: any) {
+        if (variable === null || variable === undefined) {
+            throw new Error ("Invalid 'variable' parameter passed in: null or undefined");
+        }
         let res: boolean = false;
         if (typeof type == "string") {
             res = typeof variable == type.toLowerCase();
diff --git a/commitlint/tests/testHelpers.ts b/commitlint/tests/testHelpers.ts
index c2a05026..e8d2f228 100644
--- a/commitlint/tests/testHelpers.ts
+++ b/commitlint/tests/testHelpers.ts
@@ -89,6 +89,17 @@ test("testing TypeHelpers.IsInstanceOf", () => {
     expect(TypeHelpers.IsInstanceOf(bar, Foo)).toBe(false);
 });
 
+test("testing TypeHelpers.IsInstanceOf exceptions", () => {
+    let strNull = null;
+    expect(() => TypeHelpers.IsInstanceOf(strNull, String)).toThrowError("Invalid");
+    expect(() => TypeHelpers.IsInstanceOf(strNull, String)).toThrowError("parameter");
+    expect(() => TypeHelpers.IsInstanceOf(strNull, String)).toThrowError("null");
+    let strUndefined = undefined;
+    expect(() => TypeHelpers.IsInstanceOf(strUndefined, String)).toThrowError("Invalid");
+    expect(() => TypeHelpers.IsInstanceOf(strUndefined, String)).toThrowError("parameter");
+    expect(() => TypeHelpers.IsInstanceOf(strUndefined, String)).toThrowError("undefined");
+});
+
 export function runCommitLintOnMsg(inputMsg: string) {
     // FIXME: should we .lowerCase().startsWith("win") in case it starts
     // returning Win64 in the future? thing is, our CI doesn't like this