th-fixtures: only show relevant error(s) per test #1815
Description
th-fixtures generates a Cabal package with a library for each test. The whole package is built, and the output it inspected to determine which packages failed to compile. Currently, we just parse the output to a set of library names (Set String), and we display the full cabal output after each failed test. This may lead to confusion. It would be better to instead parse the output to a map from library name to error (Map String String) so that we can display only the relevant error(s) for each failed test.