Fix isProperFraction implementation and update tests

Author: Richiealx

Sprint-3/1-implement-and-rewrite-tests/implement/2-is-proper-fraction.js

@@ -1,59 +1,70 @@
-// Implement a function isProperFraction,
-// when given two numbers, a numerator and a denominator, it should return true if
-// the given numbers form a proper fraction, and false otherwise.
+// Implement a function isProperFraction.
+// When given two numbers, a numerator and a denominator, it should return true
+// if the given numbers form a proper fraction, and false otherwise.
 
 // Assumption: The parameters are valid numbers (not NaN or Infinity).
 
-// Note: If you are unfamiliar with proper fractions, please look up its mathematical definition.
+// Definition:
+// A proper fraction is a fraction where:
+// - the denominator is not zero
+// - both numbers are non-negative
+// - the numerator is smaller than the denominator
 
 // Acceptance criteria:
-// After you have implemented the function, write tests to cover all the cases, and
-// execute the code to ensure all tests pass.
+// After implementing the function, write tests to cover all cases
+// and run the code to ensure all tests pass.
 
 function isProperFraction(numerator, denominator) {
   // A fraction with denominator 0 is invalid
   if (denominator === 0) {
     return false;
   }
 
-  // A proper fraction has absolute numerator smaller than absolute denominator
-  if (Math.abs(numerator) < Math.abs(denominator)) {
+  // Negative values are not allowed
+  if (numerator < 0 || denominator < 0) {
+    return false;
+  }
+
+  // A proper fraction must have numerator smaller than denominator
+  if (numerator < denominator) {
     return true;
   }
 
+  // All other cases are not proper fractions
   return false;
 }
 
 // The line below allows us to load the isProperFraction function into tests in other files.
 // This will be useful in the "rewrite tests with jest" step.
 module.exports = isProperFraction;
 
-// Here's our helper again
+// Helper function for simple assertions in this file
 function assertEquals(actualOutput, targetOutput) {
   console.assert(
     actualOutput === targetOutput,
     `Expected ${actualOutput} to equal ${targetOutput}`
   );
 }
 
-// TODO: Write tests to cover all cases.
-// What combinations of numerators and denominators should you test?
+// Tests to cover different combinations of numerators and denominators
 
 // Example: 1/2 is a proper fraction
 assertEquals(isProperFraction(1, 2), true);
 
-// Proper fractions
+// Proper fractions (numerator smaller than denominator)
 assertEquals(isProperFraction(3, 5), true);
-assertEquals(isProperFraction(-2, 7), true);
-assertEquals(isProperFraction(2, -7), true);
+assertEquals(isProperFraction(2, 7), true);
 
-// Improper fractions
+// Improper fractions (numerator greater than or equal to denominator)
 assertEquals(isProperFraction(5, 5), false);
 assertEquals(isProperFraction(7, 3), false);
-assertEquals(isProperFraction(-8, 4), false);
 
-// Zero numerator
+// Negative numbers should return false
+assertEquals(isProperFraction(-2, 7), false);
+assertEquals(isProperFraction(2, -7), false);
+
+// Zero numerator is allowed if denominator is positive
 assertEquals(isProperFraction(0, 5), true);
 
-// Invalid fraction (denominator 0)
-assertEquals(isProperFraction(2, 0), false);
+// Invalid fraction (denominator is zero)
+assertEquals(isProperFraction(2, 0), false);

Sprint-3/1-implement-and-rewrite-tests/rewrite-tests-with-jest/2-is-proper-fraction.test.js

@@ -2,9 +2,39 @@
 // We will use the same function, but write tests for it using Jest in this file.
 const isProperFraction = require("../implement/2-is-proper-fraction");
 
-// TODO: Write tests in Jest syntax to cover all combinations of positives, negatives, zeros, and other categories.
+// These tests cover different combinations of values such as:
+// positive numbers, negative numbers, zeros, and improper fractions.
 
-// Special case: numerator is zero
-test(`should return false when denominator is zero`, () => {
-  expect(isProperFraction(1, 0)).toEqual(false);
+describe("isProperFraction", () => {
+  // Special case: denominator is zero
+  test("should return false when denominator is zero", () => {
+    expect(isProperFraction(1, 0)).toEqual(false);
+  });
+
+  // Special case: numerator is zero
+  test("should return true when numerator is zero and denominator is positive", () => {
+    expect(isProperFraction(0, 5)).toEqual(true);
+  });
+
+  // Proper fraction: numerator is positive and less than denominator
+  test("should return true for a proper fraction", () => {
+    expect(isProperFraction(1, 2)).toEqual(true);
+    expect(isProperFraction(3, 4)).toEqual(true);
+  });
+
+  // Improper fraction: numerator is greater than or equal to denominator
+  test("should return false for an improper fraction", () => {
+    expect(isProperFraction(5, 4)).toEqual(false);
+    expect(isProperFraction(4, 4)).toEqual(false);
+  });
+
+  // Negative numerator
+  test("should return false when numerator is negative", () => {
+    expect(isProperFraction(-1, 2)).toEqual(false);
+  });
+
+  // Negative denominator
+  test("should return false when denominator is negative", () => {
+    expect(isProperFraction(1, -2)).toEqual(false);
+  });
 });