From 4aae07e914996c8d33fd9a21ece101cb6a54cfe7 Mon Sep 17 00:00:00 2001
From: Jacob Coffee <jacob@z7x.org>
Date: Thu, 15 Feb 2024 23:39:20 -0600
Subject: [PATCH] feat(pip-install): add `--dry-run` flag

---
 crates/uv/src/commands/pip_install.rs | 9 +++++++++
 crates/uv/src/main.rs                 | 6 ++++++
 2 files changed, 15 insertions(+)

diff --git a/crates/uv/src/commands/pip_install.rs b/crates/uv/src/commands/pip_install.rs
index 54c68e5d4..8d816034c 100644
--- a/crates/uv/src/commands/pip_install.rs
+++ b/crates/uv/src/commands/pip_install.rs
@@ -64,6 +64,7 @@ pub(crate) async fn pip_install(
     exclude_newer: Option<DateTime<Utc>>,
     cache: Cache,
     mut printer: Printer,
+    dry_run: bool,
 ) -> Result<ExitStatus> {
     let start = std::time::Instant::now();
 
@@ -237,6 +238,14 @@ pub(crate) async fn pip_install(
         Err(err) => return Err(err.into()),
     };
 
+    if dry_run {
+        println!("Would have installed:");
+        for package in resolution.packages() {
+            println!("  {}", package);
+        }
+        return Ok(ExitStatus::Success);
+    }
+
     // Re-initialize the in-flight map.
     let in_flight = InFlight::default();
 
diff --git a/crates/uv/src/main.rs b/crates/uv/src/main.rs
index 338ef7a02..818bffb87 100644
--- a/crates/uv/src/main.rs
+++ b/crates/uv/src/main.rs
@@ -591,6 +591,11 @@ struct PipInstallArgs {
     /// format (e.g., `2006-12-02`).
     #[arg(long, value_parser = date_or_datetime, hide = true)]
     exclude_newer: Option<DateTime<Utc>>,
+
+    /// Perform a dry run, i.e., don't actually install anything but resolve the dependencies and
+    /// print the resulting plan.
+    #[clap(long)]
+    dry_run: bool,
 }
 
 #[derive(Args)]
@@ -979,6 +984,7 @@ async fn run() -> Result<ExitStatus> {
                 args.exclude_newer,
                 cache,
                 printer,
+                args.dry_run,
             )
             .await
         }