tests.overriding: buildPythonPackage: test stdenv customisation via buildPythonPackage.override

[ShamrockLee]

This PR adds overriding tests for PR #271762

• Enable stdenv customization through (buildPython*.override { inherit stdenv; }) #271762

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

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[MattSturgeon]

Thanks for adding tests!

It'd be good if we also had tests covering the deprecated way of overriding stdenv (to avoid it breaking prematurely).

Now that you've added tests, are we ready to backport (minus release notes)?

[MattSturgeon]

Although I've approved, I would ideally like to see these changes:

1. Use kebab-case names to for test cases
2. Simplify the test-case exprs
3. Add coverage for deprecated methods of overriding stdenv

diff --git a/pkgs/test/overriding.nix b/pkgs/test/overriding.nix
index a5acddde3fef..0dc85634eae4 100644
--- a/pkgs/test/overriding.nix
+++ b/pkgs/test/overriding.nix
@@ -300,14 +300,18 @@ let
         {
           buildPythonPackage,
           emptyDirectory,
+          extraAttrs,
         }:
-        buildPythonPackage {
-          pname = "package-stub";
-          version = "0.1.0";
-          pyproject = true;
-          src = emptyDirectory;
-        }
-      ) { };
+        buildPythonPackage (
+          {
+            pname = "package-stub";
+            version = "0.1.0";
+            pyproject = true;
+            src = emptyDirectory;
+          }
+          // extraAttrs
+        )
+      ) { extraAttrs = { }; };
 
       package-stub-gcc = package-stub.override (previousArgs: {
         buildPythonPackage = previousArgs.buildPythonPackage.override {
@@ -332,16 +336,36 @@ let
         });
     in
     {
-      buildPythonPackageOverrideStdenvGCC = {
-        expr = package-stub-gcc.stdenv.cc.cc.pname == pkgs.gccStdenv.cc.cc.pname;
+      buildPythonPackage-override-gccStdenv = {
+        expr = package-stub-gcc.stdenv == pkgs.gccStdenv;
         expected = true;
       };
-      buildPythonPackageOverrideStdenvClang = {
-        expr = package-stub-clang.stdenv.cc.cc.pname == pkgs.clangStdenv.cc.cc.pname;
+      buildPythonPackage-override-clangStdenv = {
+        expr = package-stub-clang.stdenv == pkgs.clangStdenv;
         expected = true;
       };
-      buildPythonPackageOverrideStdenvLibCXX = {
-        expr = package-stub-libcxx.stdenv.cc.libcxx.pname == pkgs.libcxxStdenv.cc.libcxx.pname;
+      buildPythonPackage-override-libcxxStdenv = {
+        expr = package-stub-libcxx.stdenv == pkgs.libcxxStdenv;
+        expected = true;
+      };
+      buildPythonPackage-override-clangStdenv-deprecated = {
+        expr =
+          let
+            p = package-stub.override {
+              extraAttrs.stdenv = pkgs.clangStdenv;
+            };
+          in
+          p.stdenv == pkgs.clangStdenv;
+        expected = true;
+      };
+      overridePythonAttrs-override-clangStdenv-deprecated = {
+        expr =
+          let
+            p = package-stub.overridePythonAttrs {
+              stdenv = pkgs.clangStdenv;
+            };
+          in
+          p.stdenv == pkgs.clangStdenv;
         expected = true;
       };
 

I also tried adding this test case:

overridePythonAttrs-override-clangStdenv-deprecated-nested = {
  expr =
    let
      p = package-stub-gcc.overridePythonAttrs {
        stdenv = pkgs.clangStdenv;
      };
    in
    p.stdenv == pkgs.clangStdenv;
  expected = true;
};

However, it fails because of:

Intentionally drop the effect of overrideStdenvCompat when calling buildPython*.override.

In a separate PR, we'll need to find a better way to handle that scenario.

[ShamrockLee]

Although I've approved, I would ideally like to see these changes:

1. Use kebab-case names to for test cases

2. Simplify the test-case `expr`s

3. Add coverage for deprecated methods of overriding `stdenv`

Addressed. Thanks for your suggestions!

[ShamrockLee]

PR #470091 that backports PR #267296 needs to go first before backporting this PR.

[nixpkgs-ci]

Successfully created backport PR for release-25.11:

• [Backport release-25.11] tests.overriding: buildPythonPackage: test stdenv customisation via buildPythonPackage.override #470117