[test]: Unit Tests for PortfolioInfo Methods

Description

• Detailed Description:
  The utility methods in PortfolioInfo have no tests, leaving potential edge cases (such as an empty list or null values) unchecked. Unit tests are crucial to ensure the methods work as intended.
• How to Solve:
  1. Create a Test Class:
     Create a new JUnit test class (e.g., PortfolioInfoTest) in the test folder.
  2. Write Test Cases:
     Write tests for each method. For instance:

     @Test
     public void testCalculateTotalPortfolioValue_emptyList() {
         List<Stock> stocks = new ArrayList<>();
         double value = PortfolioInfo.calculateTotalPortfolioValue(stocks);
         assertEquals(0.0, value, 0.01);
     }
     

  3. Test Various Scenarios:
     Include tests for normal data, edge cases, and possible erroneous inputs.
  4. Run the Tests:
     Execute the test suite and ensure all tests pass.

Locate the PortfolioInfo utility and inspect each method and its inputs before creating the requested PortfolioInfoTest JUnit class. Cover normal data, empty lists, null values, and other erroneous inputs mentioned in the issue, then run the project test suite and confirm all tests pass.