Migrate io-tests from bash to pytest

.gitignore

@@ -17,3 +17,4 @@ result*
 dist-newstyle
 postgrest.hp
 postgrest.prof
+__pycache__

nix/style.nix

@@ -1,4 +1,5 @@
-{ buildEnv
+{ black
+, buildEnv
 , checkedShellScript
 , git
 , hlint
@@ -19,6 +20,9 @@ let
         # --vimgrep fixes a bug in ag: https://github.com/ggreer/the_silver_searcher/issues/753
         ${silver-searcher}/bin/ag -l --vimgrep -g '\.l?hs$' . "$rootdir" \
           | xargs ${stylish-haskell}/bin/stylish-haskell -i
+
+        # Format Python files
+        ${black}/bin/black "$rootdir" 2> /dev/null
       '';
 
   # Script to check whether any uncommited changes result from postgrest-style

nix/tests.nix

@@ -15,6 +15,7 @@
 , postgrestStatic
 , postgrestProfiled
 , procps
+, python3
 , runtimeShell
 }:
 let
@@ -74,19 +75,29 @@ let
     checkedShellScript "postgrest-test-spec-all"
       (lib.concatStringsSep "\n" testRunners);
 
+  ioTestPython =
+    python3.withPackages (ps: [
+      ps.pytest
+      ps.requests
+      ps.requests-unixsocket
+      ps.pyjwt
+      ps.pyyaml
+    ]);
+
   testIO =
     name: postgresql:
     checkedShellScript
       name
       ''
         env="$(cat ${postgrest.env})"
-        export PATH="$env/bin:${curl}/bin:${procps}/bin:${diffutils}/bin:$PATH"
+        export PATH="$env/bin:$PATH"
 
         rootdir="$(${git}/bin/git rev-parse --show-toplevel)"
         cd "$rootdir"
 
         ${cabal-install}/bin/cabal v2-build ${devCabalOptions}
-        ${cabal-install}/bin/cabal v2-exec ${withTmpDb postgresql} "$rootdir"/test/io-tests.sh
+        ${cabal-install}/bin/cabal v2-exec ${withTmpDb postgresql} \
+          ${ioTestPython}/bin/pytest -- -v "$rootdir"/test/io-tests "$@"
       '';
 
   testMemory =
@@ -117,7 +128,7 @@ buildEnv
       ] ++ testSpecVersions;
   }
   # The memory tests have large dependencies (a profiled build of PostgREST)
-  # and are run less often than the spec tests, so we don't include them in 
+  # and are run less often than the spec tests, so we don't include them in
   # the default test environment. We make them available through a separate attribute:
   // {
   memoryTests =