=== CONTEXT ===

We are experiencing issues with the `MemfsTestFileSystem` class in our test infrastructure. The main symptoms are:

1. EISDIR errors when trying to read files
2. Issues with directory creation and path resolution
3. Test failures related to file operations

=== CODE ===

@import[../tests/utils/MemfsTestFileSystem.ts]
@import[../tests/utils/TestContext.ts]
@import[../tests/utils/TestSnapshot.ts]

=== TEST STATUS ===

@cmd[npm test]

=== YOUR TASK ===

Please analyze the MemfsTestFileSystem implementation and the test failures to:

1. Identify root causes of the EISDIR errors and path resolution issues
2. Evaluate the current implementation of path handling and directory operations
3. Suggest specific improvements to fix the issues

Focus areas:
- Path resolution logic in getPath/getMemfsPath
- Directory existence checks and creation
- File vs directory handling
- Interaction between TestContext, TestSnapshot and MemfsTestFileSystem

DO NOT GUESS. DO NOT GIVE HAND-WAVY ADVICE. BE EVIDENCE-BASED, EXPLICIT, AND DECISIVE.

Provide specific code changes needed, with clear explanations of why each change is necessary.