pytestCheckHook: proof of concept of a solution to recursive imports in some modules

pkgs/development/interpreters/python/hooks/default.nix

@@ -91,12 +91,13 @@ in {
       inherit (pythonForBuild.pkgs) installer;
     };
 
-  pytestCheckHook = callPackage ({ makePythonHook, pytest }:
+  pytestCheckHook = callPackage ({ makePythonHook, pytest, which }:
     makePythonHook {
       name = "pytest-check-hook";
-      propagatedBuildInputs = [ pytest ];
+      propagatedBuildInputs = [ pytest which ];
       substitutions = {
         inherit pythonCheckInterpreter;
+        pytestPython = pytest.pythonModule;
       };
     } ./pytest-check-hook.sh) {};
 

pkgs/development/interpreters/python/hooks/pytest-check-hook.sh

@@ -27,12 +27,38 @@ function _pytestComputeDisabledTestsString () {
     echo "$result"
 }
 
+function pytestBinaryPatchPhase() {
+    # This patch of code is necessary because `python -m pytest` is known to
+    # create circular import errors in libraries that have native extensions
+    # such as libraries with Cython modules
+    #
+    # The problem of calling pytest directly is that not necessarily the pytest
+    # command will use the @pythonCheckInterpreter@ python so we copy, patch
+    # and add the pytest binary before all others using PATH prepend
+    echo "Executing pytestBinaryPatchPhase"
+    local actualEntrypoint=$(which pytest)
+    local pytestBinaryDirectory=$(mktemp -d)
+
+    PATH="$pytestBinaryDirectory:$PATH"
+
+    if (( "${NIX_DEBUG:-0}" >= 1 )); then
+        echo "pytestBinaryPatchPhase: actualEntrypoint: $actualEntrypoint"
+        echo "pytestBinaryPatchPhase: originalPythonInterpreterBin: $originalPythonInterpreterBin"
+        echo "pytestBinaryPatchPhase: pytestBinaryDirectory: $pytestBinaryDirectory"
+        echo "pytestBinaryPatchPhase: patched PATH: $PATH"
+        echo "pytestBinaryPatchPhase: which pytest: $(which pytest)"
+    fi
+    install -m 755 "$(dirname $actualEntrypoint)"/* $pytestBinaryDirectory
+    substituteInPlace "$pytestBinaryDirectory"/* \
+        --replace "@pytestPython@" "$(dirname "$(dirname "@pythonCheckInterpreter@")")"
+}
+
 function pytestCheckPhase() {
     echo "Executing pytestCheckPhase"
     runHook preCheck
 
     # Compose arguments
-    args=" -m pytest"
+    args=""
     if [ -n "$disabledTests" ]; then
         disabledTestsString=$(_pytestComputeDisabledTestsString "${disabledTests[@]}")
       args+=" -k \""$disabledTestsString"\""
@@ -50,15 +76,15 @@ function pytestCheckPhase() {
       args+=" --ignore=\"$path\""
     done
     args+=" ${pytestFlagsArray[@]}"
-    eval "@pythonCheckInterpreter@ $args"
+    eval "pytest $args"
 
     runHook postCheck
     echo "Finished executing pytestCheckPhase"
 }
 
 if [ -z "${dontUsePytestCheck-}" ] && [ -z "${installCheckPhase-}" ]; then
     echo "Using pytestCheckPhase"
-    preDistPhases+=" pytestCheckPhase"
+    preDistPhases+=" pytestBinaryPatchPhase pytestCheckPhase"
 
     # It's almost always the case that setuptoolsCheckPhase should not be ran
     # when the pytestCheckHook is being ran

pkgs/development/python-modules/itypes/default.nix

@@ -2,7 +2,7 @@
   lib,
   fetchFromGitHub,
   buildPythonPackage,
-  pytest,
+  pytestCheckHook,
 }:
 
 buildPythonPackage rec {
@@ -16,11 +16,9 @@ buildPythonPackage rec {
     sha256 = "1ljhjp9pacbrv2phs58vppz1dlxix01p98kfhyclvbml6dgjcr52";
   };
 
-  nativeCheckInputs = [ pytest ];
-  checkPhase = ''
-    mv itypes.py itypes.py.hidden
-    pytest tests.py
-  '';
+  pytestFlagsArray = [ "tests.py" ];
+
+  nativeCheckInputs = [ pytestCheckHook ];
 
   meta = with lib; {
     description = "Simple immutable types for python";