Add a case of 0 as the denominator

Author: ausiejute

implement-and-rewrite-tests/implement-tests-with-node-test/2-is-proper-fraction.test.js

@@ -38,3 +38,7 @@ test("Improper fraction with equal values", () => {
 test("Proper fraction with zero numerator", () => {
   assert.equal(isProperFraction(0, 4), true);
 });
+
+test("Improper fraction with zero denominator", () => {
+  assert.equal(isProperFraction(4, 0), false);
+});

implement-and-rewrite-tests/rewrite-tests-with-jest/2-is-proper-fraction.test.js

@@ -7,6 +7,10 @@ test(`should return false when denominator is zero`, () => {
   expect(isProperFraction(1, 0)).toEqual(false);
 });
 
+test(`should return true when numerator is zero`, () => {
+  expect(isProperFraction(0, 1)).toEqual(true);
+});
+
 test(`should return true when numerator is less than denominator`, () => {
   expect(isProperFraction(1, 2)).toEqual(true);
 });