Add test cases for find_uv_bin (#15110)

Adds test cases to unblock

- #14181
- #14182
- #14184
- #14184
- tox-dev/pre-commit-uv#70

We use a package with a symlink to the Python module to get a mock
installation of uv without building (or packaging) the uv binary. This
lets us test real patterns like `uv pip install --prefix` without
encoding logic about where things are placed during those installs.

---------

Co-authored-by: konstin <konstin@mailbox.org>

Author: zanieb

crates/uv/tests/it/common/mod.rs

@@ -78,6 +78,9 @@ mod python_find;
 #[cfg(feature = "python")]
 mod python_list;
 
+#[cfg(all(feature = "python", feature = "pypi"))]
+mod python_module;
+
 #[cfg(feature = "python-managed")]
 mod python_install;
 

crates/uv/tests/it/main.rs

@@ -153,14 +153,14 @@ fn missing_record() -> Result<()> {
     fs_err::remove_file(dist_info.join("RECORD"))?;
 
     uv_snapshot!(context.filters(), context.pip_uninstall()
-        .arg("MarkupSafe"), @r###"
+        .arg("MarkupSafe"), @r"
     success: false
     exit_code: 2
     ----- stdout -----
 
     ----- stderr -----
     error: Cannot uninstall package; `RECORD` file not found at: [SITE_PACKAGES]/MarkupSafe-2.1.3.dist-info/RECORD
-    "###
+    "
     );
 
     Ok(())

crates/uv/tests/it/pip_uninstall.rs

@@ -0,0 +1,309 @@
+use assert_cmd::assert::OutputAssertExt;
+use assert_fs::prelude::{FileWriteStr, PathChild};
+use indoc::{formatdoc, indoc};
+
+use uv_fs::Simplified;
+use uv_static::EnvVars;
+
+use crate::common::{TestContext, site_packages_path, uv_snapshot};
+
+/// Filter the user scheme, which differs between Windows and Unix.
+fn user_scheme_bin_filter() -> (String, String) {
+    if cfg!(windows) {
+        (
+            r"\[USER_CONFIG_DIR\][\\/]Python[\\/]Python\d+".to_string(),
+            "[USER_SCHEME]".to_string(),
+        )
+    } else {
+        (r"\[HOME\]/\.local".to_string(), "[USER_SCHEME]".to_string())
+    }
+}
+
+#[test]
+fn find_uv_bin_venv() {
+    let context = TestContext::new("3.12")
+        .with_filtered_python_names()
+        .with_filtered_virtualenv_bin()
+        .with_filtered_exe_suffix()
+        .with_filter(user_scheme_bin_filter());
+
+    // Install in a virtual environment
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg(context.workspace_root.join("scripts/packages/fake-uv")), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + uv==0.1.0 (from file://[WORKSPACE]/scripts/packages/fake-uv)
+    "
+    );
+
+    // We should find the binary in the virtual environment
+    uv_snapshot!(context.filters(), context.python_command()
+        .arg("-c")
+        .arg("import uv; print(uv.find_uv_bin())"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [VENV]/[BIN]/uv
+
+    ----- stderr -----
+    "
+    );
+}
+
+#[test]
+fn find_uv_bin_target() {
+    let context = TestContext::new("3.12")
+        .with_filtered_python_names()
+        .with_filtered_virtualenv_bin()
+        .with_filtered_exe_suffix()
+        .with_filter(user_scheme_bin_filter())
+        // Target installs always use "bin" on all platforms. On Windows,
+        // with_filtered_virtualenv_bin only filters "Scripts", not "bin"
+        .with_filter((r"[\\/]bin[\\/]".to_string(), "/[BIN]/".to_string()));
+
+    // Install in a target directory
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg(context.workspace_root.join("scripts/packages/fake-uv"))
+        .arg("--target")
+        .arg("target"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using CPython 3.12.[X] interpreter at: .venv/[BIN]/[PYTHON]
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + uv==0.1.0 (from file://[WORKSPACE]/scripts/packages/fake-uv)
+    "
+    );
+
+    // We should find the binary in the target directory
+    uv_snapshot!(context.filters(), context.python_command()
+        .arg("-c")
+        .arg("import uv; print(uv.find_uv_bin())")
+        .env(EnvVars::PYTHONPATH, context.temp_dir.child("target").path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [TEMP_DIR]/target/[BIN]/uv
+
+    ----- stderr -----
+    "
+    );
+}
+
+#[test]
+fn find_uv_bin_prefix() {
+    let context = TestContext::new("3.12")
+        .with_filtered_python_names()
+        .with_filtered_virtualenv_bin()
+        .with_filtered_exe_suffix()
+        .with_filter(user_scheme_bin_filter());
+
+    // Install in a prefix directory
+    let prefix = context.temp_dir.child("prefix");
+
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg(context.workspace_root.join("scripts/packages/fake-uv"))
+        .arg("--prefix")
+        .arg(prefix.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using CPython 3.12.[X] interpreter at: .venv/[BIN]/[PYTHON]
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + uv==0.1.0 (from file://[WORKSPACE]/scripts/packages/fake-uv)
+    "
+    );
+
+    // We should find the binary in the prefix directory
+    uv_snapshot!(context.filters(), context.python_command()
+        .arg("-c")
+        .arg("import uv; print(uv.find_uv_bin())")
+        .env(
+            EnvVars::PYTHONPATH,
+            site_packages_path(&context.temp_dir.join("prefix"), "python3.12"),
+        ), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Traceback (most recent call last):
+      File "<string>", line 1, in <module>
+      File "[TEMP_DIR]/prefix/[PYTHON-LIB]/site-packages/uv/_find_uv.py", line 36, in find_uv_bin
+        raise FileNotFoundError(path)
+    FileNotFoundError: [USER_SCHEME]/[BIN]/uv
+    "#
+    );
+}
+
+#[test]
+fn find_uv_bin_base_prefix() {
+    let context = TestContext::new("3.12")
+        .with_filtered_python_names()
+        .with_filtered_virtualenv_bin()
+        .with_filtered_exe_suffix()
+        .with_filter(user_scheme_bin_filter());
+
+    // Test base prefix fallback by mutating sys.base_prefix
+    // First, create a "base" environment with fake-uv installed
+    let base_venv = context.temp_dir.child("base-venv");
+    context.venv().arg(base_venv.path()).assert().success();
+
+    // Install fake-uv in the "base" venv
+    uv_snapshot!(context.filters(), context.pip_install()
+        .arg("--python")
+        .arg(base_venv.path())
+        .arg(context.workspace_root.join("scripts/packages/fake-uv")), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using Python 3.12.[X] environment at: base-venv
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + uv==0.1.0 (from file://[WORKSPACE]/scripts/packages/fake-uv)
+    "
+    );
+
+    context.venv().assert().success();
+
+    // Mutate `base_prefix` to simulate lookup in a system Python installation
+    uv_snapshot!(context.filters(), context.python_command()
+        .arg("-c")
+        .arg(format!(r#"import sys, uv; sys.base_prefix = "{}"; print(uv.find_uv_bin())"#, base_venv.path().portable_display()))
+        .env(EnvVars::PYTHONPATH, site_packages_path(base_venv.path(), "python3.12")), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Traceback (most recent call last):
+      File "<string>", line 1, in <module>
+      File "[TEMP_DIR]/base-venv/[PYTHON-LIB]/site-packages/uv/_find_uv.py", line 36, in find_uv_bin
+        raise FileNotFoundError(path)
+    FileNotFoundError: [USER_SCHEME]/[BIN]/uv
+    "#
+    );
+}
+
+#[test]
+fn find_uv_bin_in_ephemeral_environment() -> anyhow::Result<()> {
+    let context = TestContext::new("3.12")
+        .with_filtered_python_names()
+        .with_filtered_virtualenv_bin()
+        .with_filtered_exe_suffix()
+        .with_filter(user_scheme_bin_filter());
+
+    // Create a minimal pyproject.toml
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! { r#"
+        [project]
+        name = "test-project"
+        version = "1.0.0"
+        requires-python = ">=3.8"
+        dependencies = []
+        "#
+    })?;
+
+    // We should find the binary in an ephemeral `--with` environment
+    uv_snapshot!(context.filters(), context.run()
+        .arg("--with")
+        .arg(context.workspace_root.join("scripts/packages/fake-uv"))
+        .arg("python")
+        .arg("-c")
+        .arg("import uv; print(uv.find_uv_bin())"), @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Audited in [TIME]
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + uv==0.1.0 (from file://[WORKSPACE]/scripts/packages/fake-uv)
+    Traceback (most recent call last):
+      File "<string>", line 1, in <module>
+      File "[CACHE_DIR]/archive-v0/[HASH]/[PYTHON-LIB]/site-packages/uv/_find_uv.py", line 36, in find_uv_bin
+        raise FileNotFoundError(path)
+    FileNotFoundError: [USER_SCHEME]/[BIN]/uv
+    "#
+    );
+
+    Ok(())
+}
+
+#[test]
+fn find_uv_bin_in_parent_of_ephemeral_environment() -> anyhow::Result<()> {
+    let context = TestContext::new("3.12")
+        .with_filtered_python_names()
+        .with_filtered_virtualenv_bin()
+        .with_filtered_exe_suffix()
+        .with_filter(user_scheme_bin_filter());
+
+    // Add the fake-uv package as a dependency
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(&formatdoc! { r#"
+        [project]
+        name = "test-project"
+        version = "1.0.0"
+        requires-python = ">=3.8"
+        dependencies = ["uv"]
+
+        [tool.uv.sources]
+        uv = {{ path = "{}" }}
+        "#,
+        context.workspace_root.join("scripts/packages/fake-uv").portable_display()
+    })?;
+
+    // When running in an ephemeral environment, we should find the binary in the project
+    // environment
+    uv_snapshot!(context.filters(), context.run()
+        .arg("--with")
+        .arg("anyio")
+        .arg("python")
+        .arg("-c")
+        .arg("import uv; print(uv.find_uv_bin())"),
+     @r#"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + uv==0.1.0 (from file://[WORKSPACE]/scripts/packages/fake-uv)
+    Resolved 3 packages in [TIME]
+    Prepared 3 packages in [TIME]
+    Installed 3 packages in [TIME]
+     + anyio==4.3.0
+     + idna==3.6
+     + sniffio==1.3.1
+    Traceback (most recent call last):
+      File "<string>", line 1, in <module>
+      File "[SITE_PACKAGES]/uv/_find_uv.py", line 36, in find_uv_bin
+        raise FileNotFoundError(path)
+    FileNotFoundError: [USER_SCHEME]/[BIN]/uv
+    "#
+    );
+
+    Ok(())
+}

crates/uv/tests/it/python_module.rs

@@ -0,0 +1,3 @@
+This fake uv package symlinks the Python module of uv in-tree and has a fake `uv` binary, allowing
+testing of the Python module behaviors. Consumers can replace the `uv` binary with a debug binary or
+similar if they need it to actually work.

scripts/packages/fake-uv/README.md

@@ -0,0 +1,11 @@
+[project]
+name = "uv"
+version = "0.1.0"
+requires-python = ">=3.8"
+
+[tool.uv.build-backend.data]
+scripts = "scripts"
+
+[build-system]
+requires = ["uv_build>=0.8.0,<0.9"]
+build-backend = "uv_build"

scripts/packages/fake-uv/pyproject.toml

@@ -0,0 +1,4 @@
+#!/usr/bin/env sh
+
+echo "This is a fake uv binary"
+

scripts/packages/fake-uv/scripts/uv

@@ -0,0 +1 @@
+This is a fake uv binary

scripts/packages/fake-uv/scripts/uv.exe

@@ -0,0 +1 @@
+../../../python/