Add unit tests for handling invalid LiteDB files

[PanWuming]

Description

This PR adds four unit tests to handle scenarios where LiteDB attempts to open invalid database files and streams:

• Test_AddDatabase_InvalidDatabase: Tests handling of a file with invalid content.
• Test_AddDatabase_InvalidDatabase_LargeFile: Tests handling of a file with invalid content larger than 16KB.
• Test_AddDatabase_InvalidDatabase_MemoryStream: Tests handling of an invalid content stream.
• Test_AddDatabase_InvalidDatabase_LargeFile_MemoryStream: Tests handling of a large invalid content stream.

Issues

These tests are intended to address issue #2501.

Bugs Discovered

1. Test_AddDatabase_InvalidDatabase:

   • Bug: The test expected a LiteDB.LiteException to be thrown.
   • Actual: No exception was thrown.

   • Details:

     Assert.Throws() Failure
     Expected: typeof(LiteDB.LiteException)
     Actual:   (No exception was thrown)
     

2. Test_AddDatabase_InvalidDatabase_LargeFile:

   • Bug: The test expected a LiteDB.LiteException to be thrown.
   • Actual: A System.ArgumentOutOfRangeException was thrown.
   • Details:

     Assert.Throws() Failure
     Expected: typeof(LiteDB.LiteException)
     Actual:   typeof(System.ArgumentOutOfRangeException): Ticks must be between DateTime.MinValue.Ticks and DateTime.MaxValue.Ticks. (Parameter 'ticks')

3. Test_AddDatabase_InvalidDatabase_MemoryStream:

   • Bug: The test expected a LiteDB.LiteException to be thrown.
   • Actual: A System.NotSupportedException was thrown.
   • Details:

     Assert.IsType() Failure
     Expected: LiteDB.LiteException
     Actual:   System.NotSupportedException

4. Test_AddDatabase_InvalidDatabase_LargeFile_MemoryStream:

   • Bug: The test expected a LiteDB.LiteException to be thrown.
   • Actual: A System.ArgumentOutOfRangeException was thrown.
   • Details:

     Assert.IsType() Failure
     Expected: LiteDB.LiteException
     Actual:   System.ArgumentOutOfRangeException

These findings indicate that LiteDB is not handling invalid files and streams as expected, leading to different types of exceptions or no exceptions at all.

[JKamsker]

Does it also work with memorystreams? I prefer not to write on my disk.

[PanWuming]

Does it also work with memorystreams? I prefer not to write on my disk.

Thank you for your feedback. I have updated the PR with the requested MemoryStream tests and included exception outputs for debugging. Please review the latest changes.