Initialize PEP 723 script in uv lock --script (#11717)

## Summary

Like `uv add --script`, `uv lock --script` will now initialize a PEP 723
script tag if it doesn't already exist.

---------

Co-authored-by: Zanie Blue <contact@zanie.dev>

crates/uv/src/commands/project/lock.rs

@@ -10,7 +10,7 @@ use rustc_hash::{FxBuildHasher, FxHashMap};
 use tracing::debug;
 
 use uv_cache::Cache;
-use uv_client::{Connectivity, FlatIndexClient, RegistryClientBuilder};
+use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
 use uv_configuration::{
     Concurrency, Constraints, DevGroupsSpecification, DryRun, ExtrasSpecification, PreviewMode,
     Reinstall, TrustedHost, Upgrade,
@@ -41,10 +41,11 @@ use uv_workspace::{DiscoveryOptions, Workspace, WorkspaceMember};
 use crate::commands::pip::loggers::{DefaultResolveLogger, ResolveLogger, SummaryResolveLogger};
 use crate::commands::project::lock_target::LockTarget;
 use crate::commands::project::{
-    ProjectError, ProjectInterpreter, ScriptInterpreter, UniversalState,
+    init_script_python_requirement, ProjectError, ProjectInterpreter, ScriptInterpreter,
+    UniversalState,
 };
-use crate::commands::reporters::ResolverReporter;
-use crate::commands::{diagnostics, pip, ExitStatus};
+use crate::commands::reporters::{PythonDownloadReporter, ResolverReporter};
+use crate::commands::{diagnostics, pip, ExitStatus, ScriptPath};
 use crate::printer::Printer;
 use crate::settings::{ResolverSettings, ResolverSettingsRef};
 
@@ -83,7 +84,7 @@ pub(crate) async fn lock(
     python: Option<String>,
     install_mirrors: PythonInstallMirrors,
     settings: ResolverSettings,
-    script: Option<Pep723Script>,
+    script: Option<ScriptPath>,
     python_preference: PythonPreference,
     python_downloads: PythonDownloads,
     connectivity: Connectivity,
@@ -95,6 +96,33 @@ pub(crate) async fn lock(
     printer: Printer,
     preview: PreviewMode,
 ) -> anyhow::Result<ExitStatus> {
+    // If necessary, initialize the PEP 723 script.
+    let script = match script {
+        Some(ScriptPath::Path(path)) => {
+            let client_builder = BaseClientBuilder::new()
+                .connectivity(connectivity)
+                .native_tls(native_tls)
+                .allow_insecure_host(allow_insecure_host.to_vec());
+            let reporter = PythonDownloadReporter::single(printer);
+            let requires_python = init_script_python_requirement(
+                python.as_deref(),
+                &install_mirrors,
+                project_dir,
+                false,
+                python_preference,
+                python_downloads,
+                no_config,
+                &client_builder,
+                cache,
+                &reporter,
+            )
+            .await?;
+            Some(Pep723Script::init(&path, requires_python.specifiers()).await?)
+        }
+        Some(ScriptPath::Script(script)) => Some(script),
+        None => None,
+    };
+
     // Find the project requirements.
     let workspace;
     let target = if let Some(script) = script.as_ref() {

crates/uv/src/lib.rs

@@ -193,22 +193,25 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 ) => Pep723Metadata::parse(contents)?.map(Pep723Item::Stdin),
                 _ => None,
             },
+            // For `uv add --script` and `uv lock --script`, we'll create a PEP 723 tag if it
+            // doesn't already exist.
             ProjectCommand::Add(uv_cli::AddArgs {
                 script: Some(script),
                 ..
+            })
+            | ProjectCommand::Lock(uv_cli::LockArgs {
+                script: Some(script),
+                ..
             }) => match Pep723Script::read(&script).await {
                 Ok(Some(script)) => Some(Pep723Item::Script(script)),
                 Ok(None) => None,
                 Err(err) => return Err(err.into()),
             },
+            // For the remaining commands, the PEP 723 tag must exist already.
             ProjectCommand::Remove(uv_cli::RemoveArgs {
                 script: Some(script),
                 ..
             })
-            | ProjectCommand::Lock(uv_cli::LockArgs {
-                script: Some(script),
-                ..
-            })
             | ProjectCommand::Sync(uv_cli::SyncArgs {
                 script: Some(script),
                 ..
@@ -223,8 +226,6 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             }) => match Pep723Script::read(&script).await {
                 Ok(Some(script)) => Some(Pep723Item::Script(script)),
                 Ok(None) => {
-                    // TODO(charlie): `uv lock --script` should initialize the tag, if it doesn't
-                    // exist.
                     bail!(
                         "`{}` does not contain a PEP 723 metadata tag; run `{}` to initialize the script",
                         script.user_display().cyan(),
@@ -1582,12 +1583,18 @@ async fn run_project(
                     .combine(Refresh::from(args.settings.upgrade.clone())),
             );
 
-            // Unwrap the script.
-            let script = script.map(|script| match script {
-                Pep723Item::Script(script) => script,
-                Pep723Item::Stdin(..) => unreachable!("`uv lock` does not support stdin"),
-                Pep723Item::Remote(..) => unreachable!("`uv lock` does not support remote files"),
-            });
+            // If the script already exists, use it; otherwise, propagate the file path and we'll
+            // initialize it later on.
+            let script = script
+                .map(|script| match script {
+                    Pep723Item::Script(script) => script,
+                    Pep723Item::Stdin(..) => unreachable!("`uv add` does not support stdin"),
+                    Pep723Item::Remote(..) => {
+                        unreachable!("`uv add` does not support remote files")
+                    }
+                })
+                .map(ScriptPath::Script)
+                .or(args.script.map(ScriptPath::Path));
 
             Box::pin(commands::lock(
                 project_dir,

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

@@ -152,6 +152,19 @@ impl TestContext {
         self
     }
 
+    /// Add extra standard filtering for Windows-compatible missing file errors.
+    pub fn with_filtered_missing_file_error(mut self) -> Self {
+        self.filters.push((
+            regex::escape("The system cannot find the file specified. (os error 2)"),
+            "[OS ERROR 2]".to_string(),
+        ));
+        self.filters.push((
+            regex::escape("No such file or directory (os error 2)"),
+            "[OS ERROR 2]".to_string(),
+        ));
+        self
+    }
+
     /// Add extra standard filtering for executable suffixes on the current platform e.g.
     /// drops `.exe` on Windows.
     #[must_use]

crates/uv/tests/it/lock.rs

@@ -23619,34 +23619,52 @@ fn lock_script_path() -> Result<()> {
     Ok(())
 }
 
+/// `uv lock --script` should add a PEP 723 tag, if it doesn't exist already.
 #[test]
-fn lock_script_error() -> Result<()> {
-    let context = TestContext::new("3.12");
+fn lock_script_initialize() -> Result<()> {
+    let context = TestContext::new("3.12").with_filtered_missing_file_error();
 
-    uv_snapshot!(context.filters(), context.lock().arg("--script").arg("script.py"), @r###"
+    uv_snapshot!(context.filters(), context.lock().arg("--script").arg("script.py"), @r"
     success: false
     exit_code: 2
     ----- stdout -----
 
     ----- stderr -----
-    error: Failed to read `script.py` (not found); run `uv init --script script.py` to create a PEP 723 script
-    "###);
+    error: failed to read from file `script.py`: [OS ERROR 2]
+    ");
 
     let script = context.temp_dir.child("script.py");
     script.write_str(indoc! { r"
-        import anyio
+        print('Hello, world!')
        "
     })?;
 
     uv_snapshot!(context.filters(), context.lock().arg("--script").arg("script.py"), @r###"
-    success: false
-    exit_code: 2
+    success: true
+    exit_code: 0
     ----- stdout -----
 
     ----- stderr -----
-    error: `script.py` does not contain a PEP 723 metadata tag; run `uv init --script script.py` to initialize the script
+    Resolved in [TIME]
     "###);
 
+    let lock = context.read("script.py.lock");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            lock, @r###"
+        version = 1
+        revision = 1
+        requires-python = ">=3.12"
+
+        [options]
+        exclude-newer = "2024-03-25T00:00:00Z"
+        "###
+        );
+    });
+
     Ok(())
 }