Un-gate --emit-marker-expression tests via --python-platform (#9528)

These are tedious to update on non-Linux, but I think we can just use
`--python-platform` to make them work on all platforms.

crates/uv/tests/it/pip_compile.rs

@@ -10925,13 +10925,7 @@ fn dynamic_dependencies() -> Result<()> {
 
 /// This tests the marker expressions emitted when depending on a package with
 /// exciting markers like 'anyio'.
-///
-/// NOTE: This test runs on `linux` only because some of `anyio`'s markers
-/// involve querying the specific platform being used to run `uv pip compile`.
-/// Since this test was developed on Linux, the marker expression generated is
-/// coupled with the Linux platform. Other tests for other platforms could be
-/// added.
-#[cfg(all(target_os = "linux", feature = "python-patch"))]
+#[cfg(feature = "python-patch")]
 #[test]
 fn emit_marker_expression_exciting_linux() -> Result<()> {
     let context = TestContext::new("3.12.6");
@@ -10941,12 +10935,14 @@ fn emit_marker_expression_exciting_linux() -> Result<()> {
     uv_snapshot!(context
         .pip_compile()
         .arg("requirements.in")
+        .arg("--python-platform")
+        .arg("linux")
         .arg("--emit-marker-expression"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --emit-marker-expression
+    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --python-platform linux --emit-marker-expression
     # Pinned dependencies known to be valid for:
     #    python_full_version == '3.12.6' and platform_python_implementation == 'CPython' and platform_system == 'Linux'
     anyio==4.3.0
@@ -10965,10 +10961,7 @@ fn emit_marker_expression_exciting_linux() -> Result<()> {
 
 /// This tests that the marker expression emitted accounts for markers directly
 /// in `requirements.in`.
-///
-/// NOTE: This test runs on `linux` only because it requires that `sys_platform
-/// == 'linux'` evaluates to `true`.
-#[cfg(all(target_os = "linux", feature = "python-patch"))]
+#[cfg(feature = "python-patch")]
 #[test]
 fn emit_marker_expression_direct() -> Result<()> {
     let context = TestContext::new("3.12.6");
@@ -10978,12 +10971,14 @@ fn emit_marker_expression_direct() -> Result<()> {
     uv_snapshot!(context
         .pip_compile()
         .arg("requirements.in")
+        .arg("--python-platform")
+        .arg("linux")
         .arg("--emit-marker-expression"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --emit-marker-expression
+    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --python-platform linux --emit-marker-expression
     # Pinned dependencies known to be valid for:
     #    python_full_version == '3.12.6' and platform_python_implementation == 'CPython' and platform_system == 'Linux' and sys_platform == 'linux'
     anyio==4.3.0
@@ -11006,12 +11001,6 @@ fn emit_marker_expression_direct() -> Result<()> {
 /// Linux, this dependency is ignored. But the marker expression generated must
 /// have `sys_platform == 'Linux'`, since the locked set of packages might be
 /// different (and indeed are different) on other platforms.
-///
-/// NOTE: This test runs on `linux` because it requires that `sys_platform
-/// == 'macos'` evaluates to `false`. While this technically only requires
-/// `not(target_os = "macos")`, the marker expression generated during test
-/// development was on Linux. So we require Linux.
-#[cfg(target_os = "linux")]
 #[test]
 fn emit_marker_expression_conditional() -> Result<()> {
     let context = TestContext::new("3.12");
@@ -11021,12 +11010,14 @@ fn emit_marker_expression_conditional() -> Result<()> {
     uv_snapshot!(context
         .pip_compile()
         .arg("requirements.in")
+        .arg("--python-platform")
+        .arg("linux")
         .arg("--emit-marker-expression"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --emit-marker-expression
+    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --python-platform linux --emit-marker-expression
     # Pinned dependencies known to be valid for:
     #    sys_platform == 'linux'
 
@@ -11040,15 +11031,7 @@ fn emit_marker_expression_conditional() -> Result<()> {
 /// This tests the marker expressions emitted when depending on a package with
 /// a non-pypy dependency. Specifically, `pendulum` depends on `time-machine`,
 /// but not when using pypy.
-///
-/// NOTE: This test runs on `linux` because it was written on Linux. While the
-/// marker expression itself doesn't have anything in it that couples it to
-/// Linux, it is possible for the resolution to change on other platforms. For
-/// example, on Windows, the `tzdata` dependency is excluded. (It's actually
-/// not clear why. The `tzdata` dependency appears to be an unconditional
-/// dependency. And if anything, I'd expect it to be included on Windows and
-/// excluded everywhere else... Odd.)
-#[cfg(all(target_os = "linux", feature = "python-patch"))]
+#[cfg(feature = "python-patch")]
 #[test]
 fn emit_marker_expression_pypy() -> Result<()> {
     let context = TestContext::new("3.12.6");
@@ -11058,12 +11041,14 @@ fn emit_marker_expression_pypy() -> Result<()> {
     uv_snapshot!(context
         .pip_compile()
         .arg("requirements.in")
+        .arg("--python-platform")
+        .arg("linux")
         .arg("--emit-marker-expression"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --emit-marker-expression
+    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --python-platform linux --emit-marker-expression
     # Pinned dependencies known to be valid for:
     #    python_full_version == '3.12.6' and implementation_name == 'cpython'
     pendulum==3.0.0