Generated test files should be written to /tmp and not the test directory

[shannonwells]

Problem

This behavior is from the original version that this repo forked from. It writes test files to the test directory and never cleans them up. There are test files already in test/test-files, which are also used by some tests. This can be confusing for debugging and actually did confuse me when trying to debug some test failures.

Secondly, the test named "reads parquet files via http" in test/reader.js depends upon the file generated by bloomFilterIntegration.ts and that is poor test practice.

Solution

• Write generated test files to /tmp where they will be cleaned up automatically by the system. This is the kind of thing /tmp is for, and IMO this is the best choice rather than having to create and maintain cleanup test code.
• Replace hard-coded strings used throughout tests for file names and locations in test with constants and use that instead.

Test code that reads generated files will have to be correctly distinguished from test code that opens test/test-files, and point to the files in /tmp.