diff --git a/pkgs/by-name/co/conan/package.nix b/pkgs/by-name/co/conan/package.nix
index 386e59d985b0..ebd96f12693c 100644
--- a/pkgs/by-name/co/conan/package.nix
+++ b/pkgs/by-name/co/conan/package.nix
@@ -65,14 +65,11 @@ python3.pkgs.buildPythonApplication rec {
     "conan"
   ];
 
-  pytestFlagsArray = [
-    "-n"
-    "$NIX_BUILD_CORES"
-  ];
-
   disabledTests = [
     # Tests require network access
     "TestFTP"
+    # Unstable test
+    "test_shared_windows_find_libraries"
   ] ++ lib.optionals stdenv.hostPlatform.isDarwin [
     # Rejects paths containing nix
     "test_conditional_os"
diff --git a/pkgs/by-name/fi/fichub-cli/package.nix b/pkgs/by-name/fi/fichub-cli/package.nix
index 3d62d7b2a304..f694a9b99307 100644
--- a/pkgs/by-name/fi/fichub-cli/package.nix
+++ b/pkgs/by-name/fi/fichub-cli/package.nix
@@ -35,21 +35,8 @@ python3Packages.buildPythonApplication rec {
     pytestCheckHook
   ];
 
-  # The package tries to create a file under the home directory on import
-  preCheck = ''
-    export HOME=$(mktemp -d)
-  '';
-
-  pytestFlagsArray = [
-    # pytest exits with a code of 5 if no tests are selected.
-    # handle this specific case as not an error
-    "|| ([ $? = 5 ] || exit $?)"
-  ];
-
-  disabledTestPaths = [
-    # Loading tests tries to download something from pypi.org
-    "tests/test_cli.py"
-  ];
+  # Loading tests tries to download something from pypi.org
+  doCheck = false;
 
   meta = {
     description = "CLI for the fichub.net API";
diff --git a/pkgs/by-name/pi/picard/package.nix b/pkgs/by-name/pi/picard/package.nix
index e43e39e5a47d..e39f26d4a84e 100644
--- a/pkgs/by-name/pi/picard/package.nix
+++ b/pkgs/by-name/pi/picard/package.nix
@@ -62,7 +62,7 @@ pythonPackages.buildPythonApplication rec {
     pyyaml
   ];
 
-  setupPyGlobalFlags = [ "build" "--disable-autoupdate" "--localedir=$out/share/locale" ];
+  setupPyGlobalFlags = [ "build" "--disable-autoupdate" "--localedir=${placeholder "out"}/share/locale" ];
 
   preCheck = ''
     export HOME=$(mktemp -d)
diff --git a/pkgs/by-name/ro/routersploit/package.nix b/pkgs/by-name/ro/routersploit/package.nix
index 3f656e8e4578..14de115541af 100644
--- a/pkgs/by-name/ro/routersploit/package.nix
+++ b/pkgs/by-name/ro/routersploit/package.nix
@@ -39,8 +39,6 @@ python3.pkgs.buildPythonApplication rec {
   ];
 
   pytestFlagsArray = [
-    "-n"
-    "$NIX_BUILD_CORES"
     # Run the same tests as upstream does in the first round
     "tests/core/"
     "tests/test_exploit_scenarios.py"
diff --git a/pkgs/development/python-modules/bottleneck/default.nix b/pkgs/development/python-modules/bottleneck/default.nix
index 18aa852cd73b..f89ea81255e4 100644
--- a/pkgs/development/python-modules/bottleneck/default.nix
+++ b/pkgs/development/python-modules/bottleneck/default.nix
@@ -24,7 +24,8 @@ buildPythonPackage rec {
 
   nativeCheckInputs = [ pytestCheckHook ];
 
-  pytestFlagsArray = [ "$out/${python.sitePackages}" ];
+  preCheck = "pushd $out";
+  postCheck = "popd";
 
   disabledTests = [ "test_make_c_files" ];
 
diff --git a/pkgs/development/python-modules/certbot-dns-inwx/default.nix b/pkgs/development/python-modules/certbot-dns-inwx/default.nix
index 08c83c264bca..81b20f23ff79 100644
--- a/pkgs/development/python-modules/certbot-dns-inwx/default.nix
+++ b/pkgs/development/python-modules/certbot-dns-inwx/default.nix
@@ -24,7 +24,7 @@ buildPythonPackage rec {
   # Doesn't have any tests
   doCheck = false;
 
-  pytestCheckHook = [ "certbot_dns_inwx" ];
+  pytestImportsCheck = [ "certbot_dns_inwx" ];
 
   meta = with lib; {
     description = "INWX DNS Authenticator plugin for Certbot";
diff --git a/pkgs/development/python-modules/dtw-python/default.nix b/pkgs/development/python-modules/dtw-python/default.nix
index 7021d576bab4..627d16b0e062 100644
--- a/pkgs/development/python-modules/dtw-python/default.nix
+++ b/pkgs/development/python-modules/dtw-python/default.nix
@@ -39,10 +39,12 @@ buildPythonPackage rec {
   ];
 
   # We need to run tests on real built package: https://github.com/NixOS/nixpkgs/issues/255262
-  preCheck = "cd $out";
-  nativeCheckInputs = [ pytestCheckHook ];
   # tests/ are not included to output package, so we have to set path explicitly
-  pytestFlagsArray = [ "$src/tests" ];
+  preCheck = ''
+    appendToVar pytestFlagsArray "$src/tests"
+    cd $out
+  '';
+  nativeCheckInputs = [ pytestCheckHook ];
 
   pythonImportsCheck = [ "dtw" ];
 
diff --git a/pkgs/development/python-modules/iso4217/default.nix b/pkgs/development/python-modules/iso4217/default.nix
index 56945d3ed07a..b9dd6d2f9f7b 100644
--- a/pkgs/development/python-modules/iso4217/default.nix
+++ b/pkgs/development/python-modules/iso4217/default.nix
@@ -40,15 +40,15 @@ buildPythonPackage rec {
     # The table is already downloaded
     export ISO4217_DOWNLOAD=0
     # Copy the table file to satifiy the build process
-    cp -r ${table} $pname/table.xml
+    cp -r ${table} iso4217/table.xml
   '';
 
   postInstall = ''
     # Copy the table file
-    cp -r ${table} $out/${python.sitePackages}/$pname/table.xml
+    cp -r ${table} $out/${python.sitePackages}/iso4217/table.xml
   '';
 
-  pytestFlagsArray = [ "$pname/test.py" ];
+  pytestFlagsArray = [ "iso4217/test.py" ];
 
   pythonImportsCheck = [ "iso4217" ];
 
diff --git a/pkgs/development/python-modules/macaddress/default.nix b/pkgs/development/python-modules/macaddress/default.nix
index 97d07f45d1c8..137561253049 100644
--- a/pkgs/development/python-modules/macaddress/default.nix
+++ b/pkgs/development/python-modules/macaddress/default.nix
@@ -27,7 +27,7 @@ buildPythonPackage rec {
     reprshed
   ];
 
-  pytestFlagsArray = [ "$src/test.py" ];
+  pytestFlagsArray = [ "test.py" ];
 
   meta = with lib; {
     homepage = "https://github.com/mentalisttraceur/python-macaddress";
diff --git a/pkgs/development/python-modules/qcodes/default.nix b/pkgs/development/python-modules/qcodes/default.nix
index 01ae8380228c..a1c5206f4af2 100644
--- a/pkgs/development/python-modules/qcodes/default.nix
+++ b/pkgs/development/python-modules/qcodes/default.nix
@@ -148,8 +148,6 @@ buildPythonPackage rec {
 
   pytestFlagsArray = [
     "-v"
-    "-n"
-    "$NIX_BUILD_CORES"
     # Follow upstream with settings
     "-m 'not serial'"
     "--hypothesis-profile ci"
diff --git a/pkgs/development/python-modules/vapoursynth/default.nix b/pkgs/development/python-modules/vapoursynth/default.nix
index 1fb1d4be03ef..8e50bba69a4d 100644
--- a/pkgs/development/python-modules/vapoursynth/default.nix
+++ b/pkgs/development/python-modules/vapoursynth/default.nix
@@ -20,7 +20,7 @@ buildPythonPackage {
 
   unittestFlagsArray = [
     "-s"
-    "$src/test"
+    "test"
     "-p"
     "'*test.py'"
   ];