feat: option to build directly with uv (#2322)

* feat: option to build directly with uv

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

tests: add uv to tests

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

fix: uv doesn't pick special Pythons at the top of the path

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

fix: set uv build constraints too

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

fix: uv doesn't support PyPy 3.8

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

tests: add pyproject.toml for failing test

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

Revert "tests: add pyproject.toml for failing test"

This reverts commit 619bde368a67dfdd8f02dc33a1525c27bc8cbe91.

tests: skip uv output test

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* tests: uv was in the wrong fixture

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* fix: from @trim21

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* tests: improve skipping

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* fix: some fixes from copilot review

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

test/conftest.py

@@ -163,7 +163,7 @@ def build_frontend_env_nouv(request: pytest.FixtureRequest) -> dict[str, str]:
     return {"CIBW_BUILD_FRONTEND": frontend}
 
 
-@pytest.fixture(params=["pip", "build", "build[uv]"])
+@pytest.fixture(params=["pip", "build", "build[uv]", "uv"])
 def build_frontend_env(request: pytest.FixtureRequest) -> dict[str, str]:
     frontend = request.param
     marks = {m.name for m in request.node.iter_markers()}
@@ -178,10 +178,12 @@ def build_frontend_env(request: pytest.FixtureRequest) -> dict[str, str]:
 
     if platform in {"pyodide", "ios", "android"} and frontend == "pip":
         pytest.skip(f"Can't use pip as build frontend for {platform}")
-    if platform == "pyodide" and frontend == "build[uv]":
+    if platform == "android" and frontend == "uv":
+        pytest.skip(f"Can't use uv as build frontend for {platform}")
+    if platform == "pyodide" and frontend in {"build[uv]", "uv"}:
         pytest.skip("Can't use uv with pyodide yet")
     uv_path = find_uv()
-    if uv_path is None and frontend == "build[uv]":
+    if uv_path is None and frontend in {"build[uv]", "uv"}:
         pytest.skip("Can't find uv, so skipping uv tests")
     if uv_path is not None and frontend == "build" and platform not in {"android", "ios"}:
         pytest.skip("No need to check build when uv is present")