1 files changed, 137 insertions, 0 deletions
diff --git a/nixpkgs/pkgs/development/interpreters/python/hooks/python-catch-conflicts-hook-tests.nix b/nixpkgs/pkgs/development/interpreters/python/hooks/python-catch-conflicts-hook-tests.nix
new file mode 100644
index 000000000000..f3d9235799e0
--- /dev/null
+++ b/nixpkgs/pkgs/development/interpreters/python/hooks/python-catch-conflicts-hook-tests.nix
@@ -0,0 +1,137 @@
+{ pythonOnBuildForHost, runCommand, writeShellScript, coreutils, gnugrep }: let
+
+  pythonPkgs = pythonOnBuildForHost.pkgs;
+
+  ### UTILITIES
+
+  # customize a package so that its store paths differs
+  customize = pkg: pkg.overrideAttrs { some_modification = true; };
+
+  # generates minimal pyproject.toml
+  pyprojectToml = pname: builtins.toFile "pyproject.toml" ''
+    [project]
+    name = "${pname}"
+    version = "1.0.0"
+  '';
+
+  # generates source for a python project
+  projectSource = pname: runCommand "my-project-source" {} ''
+    mkdir -p $out/src
+    cp ${pyprojectToml pname} $out/pyproject.toml
+    touch $out/src/__init__.py
+  '';
+
+  # helper to reduce boilerplate
+  generatePythonPackage = args: pythonPkgs.buildPythonPackage (
+    {
+      version = "1.0.0";
+      src = runCommand "my-project-source" {} ''
+        mkdir -p $out/src
+        cp ${pyprojectToml args.pname} $out/pyproject.toml
+        touch $out/src/__init__.py
+      '';
+      pyproject = true;
+      catchConflicts = true;
+      buildInputs = [ pythonPkgs.setuptools ];
+    }
+    // args
+  );
+
+  # in order to test for a failing build, wrap it in a shell script
+  expectFailure = build: errorMsg: build.overrideDerivation (old: {
+    builder = writeShellScript "test-for-failure" ''
+      export PATH=${coreutils}/bin:${gnugrep}/bin:$PATH
+      ${old.builder} "$@" > ./log 2>&1
+      status=$?
+      cat ./log
+      if [ $status -eq 0 ] || ! grep -q "${errorMsg}" ./log; then
+        echo "The build should have failed with '${errorMsg}', but it didn't"
+        exit 1
+      else
+        echo "The build failed as expected with: ${errorMsg}"
+        mkdir -p $out
+      fi
+    '';
+  });
+in {
+
+  ### TEST CASES
+
+  # Test case which must not trigger any conflicts.
+  # This derivation has runtime dependencies on custom versions of multiple build tools.
+  # This scenario is relevant for lang2nix tools which do not override the nixpkgs fix-point.
+  # see https://github.com/NixOS/nixpkgs/issues/283695
+  ignores-build-time-deps =
+    generatePythonPackage {
+      pname = "ignores-build-time-deps";
+      buildInputs = [
+        pythonPkgs.build
+        pythonPkgs.packaging
+        pythonPkgs.setuptools
+        pythonPkgs.wheel
+      ];
+      propagatedBuildInputs = [
+        # Add customized versions of build tools as runtime deps
+        (customize pythonPkgs.packaging)
+        (customize pythonPkgs.setuptools)
+        (customize pythonPkgs.wheel)
+      ];
+    };
+
+  # Simplest test case that should trigger a conflict
+  catches-simple-conflict = let
+    # this build must fail due to conflicts
+    package = pythonPkgs.buildPythonPackage rec {
+      pname = "catches-simple-conflict";
+      version = "0.0.0";
+      src = projectSource pname;
+      pyproject = true;
+      catchConflicts = true;
+      buildInputs = [
+        pythonPkgs.setuptools
+      ];
+      # depend on two different versions of packaging
+      # (an actual runtime dependency conflict)
+      propagatedBuildInputs = [
+        pythonPkgs.packaging
+        (customize pythonPkgs.packaging)
+      ];
+    };
+  in
+    expectFailure package "Found duplicated packages in closure for dependency 'packaging'";
+
+
+  /*
+    More complex test case with a transitive conflict
+
+    Test sets up this dependency tree:
+
+      toplevel
+      ├── dep1
+      │   └── leaf
+      └── dep2
+          └── leaf (customized version -> conflicting)
+  */
+  catches-transitive-conflict = let
+    # package depending on both dependency1 and dependency2
+    toplevel = generatePythonPackage {
+      pname = "catches-transitive-conflict";
+      propagatedBuildInputs = [ dep1 dep2 ];
+    };
+    # dep1 package depending on leaf
+    dep1 = generatePythonPackage {
+      pname = "dependency1";
+      propagatedBuildInputs = [ leaf ];
+    };
+    # dep2 package depending on conflicting version of leaf
+    dep2 = generatePythonPackage {
+      pname = "dependency2";
+      propagatedBuildInputs = [ (customize leaf) ];
+    };
+    # some leaf package
+    leaf = generatePythonPackage {
+      pname = "leaf";
+    };
+  in
+    expectFailure toplevel "Found duplicated packages in closure for dependency 'leaf'";
+}