dfmt: migrate to pyproject build

The package now uses pyproject format instead of setuptools, with poetry-core as the build system. The build configuration has been updated to replace the deprecated poetry.masonry.api backend with poetry.core.masonry.api.

dfmt: add tests to dfmt

dfmt: Use poetry-core

pkgs/by-name/df/dfmt/package.nix

@@ -1,25 +1,29 @@
 {
   lib,
-  python3,
+  python3Packages,
   fetchPypi,
 }:
 
-let
-  inherit (python3.pkgs)
-    buildPythonApplication
-    pythonOlder
-    ;
-in
-buildPythonApplication rec {
+python3Packages.buildPythonApplication (finalAttrs: {
   pname = "dfmt";
   version = "1.2.0";
-  format = "setuptools";
+  pyproject = true;
+
+  build-system = [
+    python3Packages.poetry-core
+  ];
 
   src = fetchPypi {
-    inherit pname version;
-    sha256 = "7af6360ca8d556f1cfe82b97f03b8d1ea5a9d6de1fa3018290c844b6566d9d6e";
+    inherit (finalAttrs) pname version;
+    hash = "sha256-evY2DKjVVvHP6CuX8DuNHqWp1t4fowGCkMhEtlZtnW4=";
   };
 
+  postPatch = ''
+    substituteInPlace pyproject.toml \
+      --replace-fail 'poetry.masonry.api' 'poetry.core.masonry.api' \
+      --replace-fail 'poetry>=' 'poetry-core>=' \
+  '';
+
   meta = {
     description = "Format paragraphs, comments and doc strings";
     mainProgram = "dfmt";
@@ -27,4 +31,4 @@ buildPythonApplication rec {
     license = lib.licenses.bsd3;
     maintainers = with lib.maintainers; [ cole-h ];
   };
-}
+})