From 9371b60d71e69d03d9ec643bdfb88a499a3ed76e Mon Sep 17 00:00:00 2001
From: Pam Selle <204372+pselle@users.noreply.github.com>
Date: Tue, 12 Jan 2021 13:21:25 -0500
Subject: [PATCH] More verbose error for whole resource move failure

When running state mv with a resource source, but the destination
fails, provide a hint that the source is a resource (not an instance)
in case the user means to address it this way
---
 command/state_mv.go      | 2 +-
 command/state_mv_test.go | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/command/state_mv.go b/command/state_mv.go
index 818811ddf8..20282382a0 100644
--- a/command/state_mv.go
+++ b/command/state_mv.go
@@ -184,7 +184,7 @@ func (c *StateMvCommand) Run(args []string) int {
 				diags = diags.Append(tfdiags.Sourceless(
 					tfdiags.Error,
 					msgInvalidTarget,
-					fmt.Sprintf("Cannot move %s to %s: the target must also be a whole resource.", addrFrom, destAddr),
+					fmt.Sprintf("Cannot move %s to %s: the source is a whole resource (not a resource instance) so the target must also be a whole resource.", addrFrom, destAddr),
 				))
 				c.showDiagnostics(diags)
 				return 1
diff --git a/command/state_mv_test.go b/command/state_mv_test.go
index 558246b5c9..b9c21e5b76 100644
--- a/command/state_mv_test.go
+++ b/command/state_mv_test.go
@@ -293,8 +293,9 @@ func TestStateMv_resourceToInstanceErr(t *testing.T) {
 	expectedErr := `
 Error: Invalid target address
 
-Cannot move test_instance.foo to test_instance.bar[0]: the target must also be
-a whole resource.
+Cannot move test_instance.foo to test_instance.bar[0]: the source is a whole
+resource (not a resource instance) so the target must also be a whole
+resource.
 
 `
 	errOutput := ui.ErrorWriter.String()