Add tests for empty index URL environment variable (#2141)

crates/uv/tests/pip_compile.rs

@@ -4517,3 +4517,124 @@ fn editable_direct_dependency() -> Result<()> {
 
     Ok(())
 }
+
+/// Setting `UV_INDEX_URL` to the empty string should treat it as "unset".
+#[test]
+fn empty_index_url_env_var() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("anyio")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--emit-index-url")
+            .env("UV_INDEX_URL", ""), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2023-11-18T12:00:00Z requirements.in --emit-index-url
+    --index-url https://pypi.org/simple
+
+    anyio==4.0.0
+    idna==3.4
+        # via anyio
+    sniffio==1.3.0
+        # via anyio
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    "###
+    );
+
+    Ok(())
+}
+
+/// Setting `EXTRA_UV_INDEX_URL` to the empty string should treat it as "unset".
+#[test]
+fn empty_extra_index_url_env_var() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("anyio")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--emit-index-url")
+            .env("EXTRA_UV_INDEX_URL", ""), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2023-11-18T12:00:00Z requirements.in --emit-index-url
+    --index-url https://pypi.org/simple
+
+    anyio==4.0.0
+    idna==3.4
+        # via anyio
+    sniffio==1.3.0
+        # via anyio
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    "###
+    );
+
+    Ok(())
+}
+
+/// Setting `UV_INDEX_URL` to the empty string should treat it as "unset", and so should be
+/// overridden by an `--index-url` in a requirements file.
+#[test]
+fn empty_index_url_env_var_override() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("--index-url https://test.pypi.org/simple\nidna")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--emit-index-url")
+            .env("UV_INDEX_URL", ""), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2023-11-18T12:00:00Z requirements.in --emit-index-url
+    --index-url https://test.pypi.org/simple
+
+    idna==2.7
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    "###
+    );
+
+    Ok(())
+}
+
+/// The `UV_INDEX_URL` should override an `--index-url` in a requirements file.
+#[test]
+fn index_url_env_var_override() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("--index-url https://pypi.org/simple\nidna")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--emit-index-url")
+            .env("UV_INDEX_URL", "https://test.pypi.org/simple"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2023-11-18T12:00:00Z requirements.in --emit-index-url
+    --index-url https://test.pypi.org/simple
+
+    idna==2.7
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    "###
+    );
+
+    Ok(())
+}