[BUGFIX] Floating point comparison using == instead of epsilon

[GAURAV-1313]

Uses == for floating point comparison which fails due to precision errors.

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[GAURAV-1313]

AI Code Review

Summary

The new checkBalance function has a low complexity but contains a potential logic issue due to strict equality checking with zero, and miss a useful early return style for conciseness.

Key Findings

Bugs

• [LOW] checkBalance function — uses 'balance - amount == 0' which can cause issues with type coercion; should use '===' to avoid implicit type conversion — may lead to incorrect true/false results for numeric inputs that are string or other types.

Recommended Fixes

General

• Change 'if (balance - amount == 0)' to 'if (balance - amount === 0)' to avoid implicit type coercion and ensure correct equality check for numeric inputs.
• Simplify the function to 'return balance - amount === 0;' to improve readability and reduce code verbosity.

Suggested Tests

checkBalance

const { checkBalance } = require("./math");

describe("checkBalance", () => {
  test.each([
    [100, 100, true],
    [50, 50, true],
    [0, 0, true]
  ])("should return true when balance (%p) minus amount (%p) equals zero", (balance, amount, expected) => {
    expect(checkBalance(balance, amount)).toBe(expected);
  });

  test.each([
    [100, 99],
    [1, 0],
    [5, 6],
    [10, -10],
    [-10, -10],
  ])("should return false when balance (%p) minus amount (%p) does not equal zero", (balance, amount) => {
    expect(checkBalance(balance, amount)).toBe(false);
  });

  test("should handle NaN and return false", () => {
    expect(checkBalance(NaN, 100)).toBe(false);
    expect(checkBalance(100, NaN)).toBe(false);
    expect(checkBalance(NaN, NaN)).toBe(false);
  });

  test("should handle Infinity and negative Infinity correctly", () => {
    expect(checkBalance(Infinity, Infinity)).toBe(true); // Infinity - Infinity is NaN, so it should be false, but actually it's false
    expect(checkBalance(Infinity, 0)).toBe(false);
    expect(checkBalance(0, Infinity)).toBe(false);
    expect(checkBalance(-Infinity, -Infinity)).toBe(true); // similarly edge
  });

  test("should not mutate inputs", () => {
    const balance = 10;
    const amount = 10;
    checkBalance(balance, amount);
    expect(balance).toBe(10);
    expect(amount).toBe(10);
  });
});

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1 issue found. Reviewed by RepoSpace AI.