How to build the testsuite?

What is the magic trick to build (and run) the testsuite?
Build fails because of the dependency cycle `pretty:test -> containers -> template-haskell -> ghc-boot-th -> pretty`.
```
$ cabal build --enable-tests
Could not resolve dependencies:
[__0] trying: pretty-1.1.3.6 (user goal)
[__1] trying: pretty:*test
[__2] trying: QuickCheck-2.16.0.0 (dependency of pretty *test)
[__3] trying: splitmix-0.1.3.1 (dependency of QuickCheck)
[__4] trying: containers-0.7/installed-f896 (dependency of QuickCheck)
[__5] trying: template-haskell-2.23.0.0/installed-9d0c (dependency of containers)
[__6] next goal: ghc-boot-th (dependency of template-haskell)
[__6] rejecting: ghc-boot-th-9.12.2/installed-9353 (package is broken, missing dependency pretty-1.1.3.6-1375)
[__6] rejecting: ghc-boot-th; 9.10.2, 9.10.1, 9.8.1, 9.6.6, 9.6.3, 9.6.1, 9.4.1, 9.2.2, 9.2.1, 9.0.1, 8.10.2, 8.10.1, 8.8.3, 8.8.1, 8.6.5, 8.6.4, 8.6.1, 8.4.4, 8.4.3, 8.4.2, 8.4.1, 8.2.2, 8.2.1, 8.0.2, 8.0.1 (conflict: template-haskell => ghc-boot-th==9.12.2/installed-9353)
[__6] fail (backjumping, conflict set: ghc-boot-th, template-haskell)
```
The cycle could maybe be broken if `containers` made `template-haskell` optional:
- https://github.com/haskell/containers/issues/1156