diff --git a/crates/uv/tests/common/mod.rs b/crates/uv/tests/common/mod.rs
index 5fac438b3..7987d3011 100644
--- a/crates/uv/tests/common/mod.rs
+++ b/crates/uv/tests/common/mod.rs
@@ -6,7 +6,7 @@ use std::env;
 use std::ffi::OsString;
 use std::iter::Iterator;
 use std::path::{Path, PathBuf};
-use std::process::{Command, Output};
+use std::process::{Command, ExitStatus, Output};
 use std::str::FromStr;
 
 use assert_cmd::assert::{Assert, OutputAssertExt};
@@ -559,6 +559,14 @@ impl TestContext {
         command
     }
 
+    /// Create a `uv add --no-sync` command for the given requirements.
+    pub fn add_no_sync(&self, reqs: &[&str]) -> Command {
+        let mut command = Command::new(get_bin());
+        command.arg("add").arg("--no-sync").args(reqs);
+        self.add_shared_args(&mut command);
+        command
+    }
+
     /// Create a `uv remove` command for the given requirements.
     pub fn remove(&self, reqs: &[&str]) -> Command {
         let mut command = Command::new(get_bin());
@@ -567,6 +575,14 @@ impl TestContext {
         command
     }
 
+    /// Create a `uv remove --no-sync` command for the given requirements.
+    pub fn remove_no_sync(&self, reqs: &[&str]) -> Command {
+        let mut command = Command::new(get_bin());
+        command.arg("remove").arg("--no-sync").args(reqs);
+        self.add_shared_args(&mut command);
+        command
+    }
+
     /// Create a `uv tree` command with options shared across scenarios.
     pub fn tree(&self) -> Command {
         let mut command = Command::new(get_bin());
@@ -738,6 +754,51 @@ impl TestContext {
         let project_dir = PathBuf::from(format!("../../ecosystem/{name}"));
         self.temp_dir.copy_from(project_dir, &["*"]).unwrap();
     }
+
+    /// Creates a way to compare the changes made to a lock file.
+    ///
+    /// This routine starts by copying (not moves) the generated lock file to
+    /// memory. It then calls the given closure with this test context to get a
+    /// `Command` and runs the command. The diff between the old lock file and
+    /// the new one is then returned.
+    ///
+    /// This assumes that a lock has already been performed.
+    pub fn diff_lock(&self, change: impl Fn(&TestContext) -> Command) -> String {
+        static TRIM_TRAILING_WHITESPACE: std::sync::LazyLock<Regex> =
+            std::sync::LazyLock::new(|| Regex::new(r"(?m)^\s+$").unwrap());
+
+        let lock_path = ChildPath::new(self.temp_dir.join("uv.lock"));
+        let old_lock = fs_err::read_to_string(&lock_path).unwrap();
+        let (snapshot, _, status) = run_and_format_with_status(
+            change(self),
+            self.filters(),
+            "diff_lock",
+            Some(crate::common::WindowsFilters::Platform),
+        );
+        assert!(status.success(), "{snapshot}");
+        let new_lock = fs_err::read_to_string(&lock_path).unwrap();
+        diff_snapshot(&old_lock, &new_lock)
+    }
+}
+
+/// Creates a "unified" diff between the two line-oriented strings suitable
+/// for snapshotting.
+pub fn diff_snapshot(old: &str, new: &str) -> String {
+    static TRIM_TRAILING_WHITESPACE: std::sync::LazyLock<Regex> =
+        std::sync::LazyLock::new(|| Regex::new(r"(?m)^\s+$").unwrap());
+
+    let diff = similar::TextDiff::from_lines(old, new);
+    let unified = diff
+        .unified_diff()
+        .context_radius(10)
+        .header("old", "new")
+        .to_string();
+    // Not totally clear why, but some lines end up containing only
+    // whitespace in the diff, even though they don't appear in the
+    // original data. So just strip them here.
+    TRIM_TRAILING_WHITESPACE
+        .replace_all(&unified, "")
+        .into_owned()
 }
 
 pub fn site_packages_path(venv: &Path, python: &str) -> PathBuf {
@@ -869,11 +930,25 @@ pub enum WindowsFilters {
 ///
 /// This function is derived from `insta_cmd`s `spawn_with_info`.
 pub fn run_and_format<T: AsRef<str>>(
-    mut command: impl BorrowMut<Command>,
+    command: impl BorrowMut<Command>,
     filters: impl AsRef<[(T, T)]>,
     function_name: &str,
     windows_filters: Option<WindowsFilters>,
 ) -> (String, Output) {
+    let (snapshot, output, _) =
+        run_and_format_with_status(command, filters, function_name, windows_filters);
+    (snapshot, output)
+}
+
+/// Execute the command and format its output status, stdout and stderr into a snapshot string.
+///
+/// This function is derived from `insta_cmd`s `spawn_with_info`.
+pub fn run_and_format_with_status<T: AsRef<str>>(
+    mut command: impl BorrowMut<Command>,
+    filters: impl AsRef<[(T, T)]>,
+    function_name: &str,
+    windows_filters: Option<WindowsFilters>,
+) -> (String, Output, ExitStatus) {
     let program = command
         .borrow_mut()
         .get_program()
@@ -955,7 +1030,8 @@ pub fn run_and_format<T: AsRef<str>>(
         }
     }
 
-    (snapshot, output)
+    let status = output.status;
+    (snapshot, output, status)
 }
 
 /// Recursively copy a directory and its contents.