Better error messages for unsupported uninstall arguments

Instead of parsing whatever string the user supplied as the tool name
and supplying a default `VersionSpec`, attempt to parse the value as a
full specifier which may include a version. This means we can provide
better errors when the user passes a version. Specifically we can report
that Volta does not yet support uninstalling specific versions of tools.
Previously, we would report something like this:

```
warning:  No package '[email protected]' found to uninstall
```

Notice that the old message treated `'[email protected]'` as the name of
the tool, when it should have been treating it as a tool and a version
specifier. Now, we instead report that uninstalling specific versions of
tools is unsupported.

The original motivation here was noticing that we printed errors like
that if the user tried to uninstall a runtime or a package manager with
a version specifier. This fixes that as well, since it no longer parses
a string like `[email protected]` as a package, but rather as a runtime and
version specifier, and can fall into the normal handling for runtimes.

Author: chriskrycho

src/command/uninstall.rs

@@ -1,4 +1,4 @@
-use volta_core::error::{ExitCode, Fallible};
+use volta_core::error::{ErrorKind, ExitCode, Fallible};
 use volta_core::session::{ActivityKind, Session};
 use volta_core::tool;
 use volta_core::version::VersionSpec;
@@ -15,8 +15,20 @@ impl Command for Uninstall {
     fn run(self, session: &mut Session) -> Fallible<ExitCode> {
         session.add_event_start(ActivityKind::Uninstall);
 
-        let version = VersionSpec::default();
-        let tool = tool::Spec::from_str_and_version(&self.tool, version);
+        let tool = tool::Spec::try_from_str(&self.tool)?;
+
+        // For packages, specifically report that we do not support uninstalling
+        // specific versions. For runtimes and package managers, we currently
+        // *intentionally* let this fall through to inform the user that we do
+        // not support uninstalling those *at all*.
+        if let tool::Spec::Package(_name, version) = &tool {
+            let VersionSpec::None = version else {
+                return Err(ErrorKind::Unimplemented {
+                    feature: "uninstalling specific versions of tools".into(),
+                }
+                .into());
+            };
+        }
 
         tool.uninstall()?;
 

tests/acceptance/volta_uninstall.rs

@@ -96,6 +96,8 @@ fn uninstall_package_basic() {
     assert!(!Sandbox::package_image_exists("cowsay"));
 }
 
+// The setup here is the same as the above, but here we check to make sure that
+// if the user supplies a version, we error correctly.
 #[test]
 fn uninstall_package_basic_with_version() {
     // basic uninstall - everything exists, and everything except the cached
@@ -116,14 +118,6 @@ fn uninstall_package_basic_with_version() {
             "[..]error: uninstalling specific versions of tools is not supported yet."
         )
     );
-
-    // check that nothing is deleted.
-    assert!(Sandbox::package_config_exists("cowsay"));
-    assert!(Sandbox::bin_config_exists("cowsay"));
-    assert!(Sandbox::bin_config_exists("cowthink"));
-    assert!(Sandbox::shim_exists("cowsay"));
-    assert!(Sandbox::shim_exists("cowthink"));
-    assert!(Sandbox::package_image_exists("cowsay"));
 }
 
 #[test]
@@ -210,3 +204,14 @@ fn uninstall_package_orphaned_bins() {
     assert!(!Sandbox::shim_exists("cowsay"));
     assert!(!Sandbox::shim_exists("cowthink"));
 }
+
+#[test]
+fn uninstall_runtime() {
+    let s = sandbox().build();
+    assert_that!(
+        s.volta("uninstall node"),
+        execs()
+            .with_status(1)
+            .with_stderr_contains("[..]error: Uninstalling node is not supported yet.")
+    )
+}