Improve gematriya test coverage with zero and negative number

Author: mjradwin

src/gematriya.ts

@@ -68,8 +68,8 @@ function num2digits(num: number): number[] {
 export function gematriya(num: number | string): string {
   const num0 = <string>num;
   const num1 = parseInt(num0, 10);
-  if (!num1) {
-    throw new TypeError(`invalid parameter to gematriya ${num}`);
+  if (!num1 || num1 < 0) {
+    throw new TypeError(`invalid gematriya number: ${num}`);
   }
   let str = '';
   const thousands = Math.floor(num1 / 1000);

test/gematriya.spec.ts

@@ -49,3 +49,15 @@ test('gematriyaStrToNum-thousands', () => {
   expect(gematriyaStrToNum('א׳קכ״ג')).toBe(1123);
   expect(gematriyaStrToNum('ז׳ז׳')).toBe(7007);
 });
+
+test('throws-0', () => {
+  expect(() => {
+    gematriya(NaN);
+  }).toThrow('invalid gematriya number: NaN');
+  expect(() => {
+    gematriya(0);
+  }).toThrow('invalid gematriya number: 0');
+  expect(() => {
+    gematriya(-34);
+  }).toThrow('invalid gematriya number: -34');
+});