A difference is not obvious when two sets are compared:
there might be just one different element, but
sets would be printed in one line in iteration order
(which is non-fixed for hashsets).
Also the properties:
EXPECTED_JS_FILES_IN_OUTPUT_FOR_STDLIB_ONLY,
EXPECTED_JS_FILES_IN_OUTPUT_FOR_MODULE_STDLIB_ONLY,
EXPECTED_JS_FILES_IN_OUTPUT_NO_COPY,
EXPECTED_JS_FILES_IN_OUTPUT_WITH_ADDITIONAL_LIB_AND_DEFAULT_DIR,
EXPECTED_JS_FILES_IN_OUTPUT_WITH_ADDITIONAL_LIB_AND_CUSTOM_DIR
are hard to distinguish in code and are not convenient to edit.
Alexey Tsvetkov