gopls/internal/settings: rename goTest code action to source.test

Change-Id: I0ef0285cd35e32d259a7dc0bb9712ff61d99f3f6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/604795
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

gopls/doc/features/transformation.md

@@ -80,6 +80,18 @@ for the current selection.
      recognized by gopls that enables corresponding logic in the
      server's ApplyFix command handler. -->
 
+<!-- The source.test ("Run this test") code action (not a
+     transformation) runs the selected test. However, it is not
+     offered by default because:
+     (a) VS Code has a richer test UX (with richer ones to come--see
+         https://github.com/golang/vscode-go/issues/1641) and
+     (b) LSP has no good way to display the streaming output of a test
+         in the client's natural UX (see last paragraph of first note
+	 of https://github.com/golang/go/issues/67400).
+     It is only offered when the "only" field includes kind source.test.
+     Should it be documented? If so, where?
+-->
+
 Caveats:
 - Many of gopls code transformations are limited by Go's syntax tree
   representation, which currently records comments not in the tree

gopls/internal/settings/codeactionkind.go

@@ -80,6 +80,6 @@ const (
 	GoAssembly       protocol.CodeActionKind = "source.assembly"
 	GoDoc            protocol.CodeActionKind = "source.doc"
 	GoFreeSymbols    protocol.CodeActionKind = "source.freesymbols"
-	GoTest           protocol.CodeActionKind = "goTest" // TODO(adonovan): rename "source.test"
+	GoTest           protocol.CodeActionKind = "source.test"
 	GoplsDocFeatures protocol.CodeActionKind = "gopls.doc.features"
 )