fix(update): check version exists before confirming uninstall

Previously, `spacetime version uninstall <ver>` would show a y/N
confirmation prompt even when the version wasn't installed, then fail
with a cryptic "No such file or directory (os error 2)" after the user
confirmed.

Now the command checks if the version directory exists before prompting,
and returns a clear error: "v{ver} is not installed".

Added 4 unit tests covering:
- Nonexistent version errors before prompt
- Current version cannot be uninstalled
- "current" keyword cannot be uninstalled
- Successful uninstall removes the version directory

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

Author: euxaristia

crates/update/src/cli/uninstall.rs

@@ -28,10 +28,97 @@ impl Uninstall {
             Ok(None) => {}
             Err(e) => tracing::warn!("{e:#}"),
         }
+        let dir = paths.cli_bin_dir.version_dir(&version);
+        if !dir.0.exists() {
+            anyhow::bail!("v{version} is not installed");
+        }
         if yes.confirm(format!("Uninstall v{version}?"))? {
-            let dir = paths.cli_bin_dir.version_dir(&version);
-            std::fs::remove_dir_all(dir)?;
+            std::fs::remove_dir_all(&dir)?;
         }
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use spacetimedb_paths::FromPathUnchecked;
+    use spacetimedb_paths::RootDir;
+
+    fn make_temp_paths() -> (tempfile::TempDir, SpacetimePaths) {
+        let tmp = tempfile::tempdir().unwrap();
+        let base = tmp.path().join("spacetime");
+        std::fs::create_dir_all(&base).unwrap();
+        let root = RootDir::from_path_unchecked(base);
+        let paths = SpacetimePaths::from_root_dir(&root);
+        (tmp, paths)
+    }
+
+    #[test]
+    fn test_uninstall_nonexistent_version_errors_before_prompt() {
+        let (_tmp, paths) = make_temp_paths();
+        let uninstall = Uninstall {
+            version: "9.9.9".to_owned(),
+            yes: ForceYes { yes: true },
+        };
+        let result = uninstall.exec(&paths);
+        assert!(result.is_err());
+        let err = result.unwrap_err();
+        assert!(
+            err.to_string().contains("9.9.9"),
+            "error should mention the version number"
+        );
+        assert!(
+            err.to_string().contains("not installed"),
+            "error should say 'not installed'"
+        );
+    }
+
+    #[test]
+    fn test_uninstall_current_version_errors() {
+        let (_tmp, paths) = make_temp_paths();
+        // Create the "current" symlink target so it exists on disk
+        let current_dir = paths.cli_bin_dir.version_dir("2.0.0");
+        std::fs::create_dir_all(&current_dir.0).unwrap();
+        paths.cli_bin_dir.set_current_version("2.0.0").unwrap();
+
+        let uninstall = Uninstall {
+            version: "2.0.0".to_owned(),
+            yes: ForceYes { yes: true },
+        };
+        let result = uninstall.exec(&paths);
+        assert!(result.is_err());
+        assert!(result.unwrap_err().to_string().contains("currently used version"),);
+    }
+
+    #[test]
+    fn test_uninstall_current_keyword_errors() {
+        let (_tmp, paths) = make_temp_paths();
+        let uninstall = Uninstall {
+            version: "current".to_owned(),
+            yes: ForceYes { yes: true },
+        };
+        let result = uninstall.exec(&paths);
+        assert!(result.is_err());
+        assert!(result.unwrap_err().to_string().contains("cannot remove `current`"),);
+    }
+
+    #[test]
+    fn test_uninstall_existing_version_with_yes() {
+        let (_tmp, paths) = make_temp_paths();
+        let version_dir = paths.cli_bin_dir.version_dir("1.0.0");
+        std::fs::create_dir_all(&version_dir.0).unwrap();
+        // Create a dummy file so we can verify the directory existed
+        std::fs::write(version_dir.0.join("spacetime"), "dummy").unwrap();
+
+        assert!(version_dir.0.exists(), "version dir should exist before");
+
+        let uninstall = Uninstall {
+            version: "1.0.0".to_owned(),
+            yes: ForceYes { yes: true },
+        };
+        uninstall.exec(&paths).unwrap();
+
+        assert!(!version_dir.0.exists(), "version dir should be removed after uninstall");
+    }
+}