tests: add HexToDecimal.test.js (#1662)

Conversions/test/HexToDecimal.test.js

@@ -0,0 +1,24 @@
+import { hexToDecimal } from '../HexToDecimal'
+
+describe('Testing HexToDecimal', () => {
+  it.each([
+    ['0', 0],
+    ['1', 1],
+    ['A', 10],
+    ['B', 11],
+    ['C', 12],
+    ['D', 13],
+    ['E', 14],
+    ['F', 15],
+    ['10', 16],
+    ['859', 2137],
+    ['4D2', 1234],
+    ['81323ABD92', 554893491602]
+  ])('check with %s', (hexStr, expected) => {
+    expect(hexToDecimal(hexStr)).toBe(expected)
+  })
+
+  it.each(['a', '-1', 'G', ''])('throws for %s', (hexStr) => {
+    expect(() => hexToDecimal(hexStr)).toThrowError()
+  })
+})