allow moving resource to new modules not in state

Create the missing modules in the state when moving resources to a
module that doesn't yet exist. This allows for refactoring of
configuration into new modules, without having to create dummy resources
in the module before the "state mv" operations.

command/state_mv.go

@@ -194,11 +194,8 @@ func (c *StateMvCommand) Run(args []string) int {
 			}
 			diags = diags.Append(c.validateResourceMove(addrFrom, addrTo))
 			if stateTo.Module(addrTo.Module) == nil {
-				diags = diags.Append(tfdiags.Sourceless(
-					tfdiags.Error,
-					msgInvalidTarget,
-					fmt.Sprintf("Cannot move to %s: %s does not exist in the current state.", addrTo, addrTo.Module),
-				))
+				// moving something to a mew module, so we need to ensure it exists
+				stateTo.EnsureModule(addrTo.Module)
 			}
 			if stateTo.Resource(addrTo) != nil {
 				diags = diags.Append(tfdiags.Sourceless(
@@ -251,11 +248,8 @@ func (c *StateMvCommand) Run(args []string) int {
 			diags = diags.Append(c.validateResourceMove(addrFrom.ContainingResource(), addrTo.ContainingResource()))
 
 			if stateTo.Module(addrTo.Module) == nil {
-				diags = diags.Append(tfdiags.Sourceless(
-					tfdiags.Error,
-					msgInvalidTarget,
-					fmt.Sprintf("Cannot move to %s: %s does not exist in the current state.", addrTo, addrTo.Module),
-				))
+				// moving something to a mew module, so we need to ensure it exists
+				stateTo.EnsureModule(addrTo.Module)
 			}
 			if stateTo.ResourceInstance(addrTo) != nil {
 				diags = diags.Append(tfdiags.Sourceless(

command/state_mv_test.go

@@ -765,6 +765,70 @@ func TestStateMv_stateOutNew_nestedModule(t *testing.T) {
 	testStateOutput(t, backups[0], testStateMvNestedModule_stateOutOriginal)
 }
 
+func TestStateMv_toNewModule(t *testing.T) {
+	state := states.BuildState(func(s *states.SyncState) {
+		s.SetResourceInstanceCurrent(
+			addrs.Resource{
+				Mode: addrs.ManagedResourceMode,
+				Type: "test_instance",
+				Name: "bar",
+			}.Instance(addrs.NoKey).Absolute(addrs.RootModuleInstance),
+			&states.ResourceInstanceObjectSrc{
+				AttrsJSON: []byte(`{"id":"bar","foo":"value","bar":"value"}`),
+				Status:    states.ObjectReady,
+			},
+			addrs.ProviderConfig{Type: "test"}.Absolute(addrs.RootModuleInstance),
+		)
+	})
+
+	statePath := testStateFile(t, state)
+	stateOutPath1 := statePath + ".out1"
+	stateOutPath2 := statePath + ".out2"
+
+	p := testProvider()
+	ui := new(cli.MockUi)
+	c := &StateMvCommand{
+		StateMeta{
+			Meta: Meta{
+				testingOverrides: metaOverridesForProvider(p),
+				Ui:               ui,
+			},
+		},
+	}
+
+	args := []string{
+		"-state", statePath,
+		"-state-out", stateOutPath1,
+		"test_instance.bar",
+		"module.bar.test_instance.bar",
+	}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+
+	// Test it is correct
+	testStateOutput(t, stateOutPath1, testStateMvNewModule_stateOut)
+	testStateOutput(t, statePath, testStateMvNestedModule_stateOutSrc)
+
+	// Test we have backups
+	backups := testStateBackups(t, filepath.Dir(statePath))
+	if len(backups) != 1 {
+		t.Fatalf("bad: %#v", backups)
+	}
+	testStateOutput(t, backups[0], testStateMvNewModule_stateOutOriginal)
+
+	// now verify we can move the module itself
+	args = []string{
+		"-state", stateOutPath1,
+		"-state-out", stateOutPath2,
+		"module.bar",
+		"module.foo",
+	}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
+	}
+	testStateOutput(t, stateOutPath2, testStateMvModuleNewModule_stateOut)
+}
 func TestStateMv_withinBackend(t *testing.T) {
 	td := tempDir(t)
 	copy.CopyDir(testFixturePath("backend-unchanged"), td)
@@ -1129,6 +1193,34 @@ module.bar.child2:
     foo = value
 `
 
+const testStateMvNewModule_stateOut = `
+<no state>
+module.bar:
+  test_instance.bar:
+    ID = bar
+    provider = provider.test
+    bar = value
+    foo = value
+`
+
+const testStateMvModuleNewModule_stateOut = `
+<no state>
+module.foo:
+  test_instance.bar:
+    ID = bar
+    provider = provider.test
+    bar = value
+    foo = value
+`
+
+const testStateMvNewModule_stateOutOriginal = `
+test_instance.bar:
+  ID = bar
+  provider = provider.test
+  bar = value
+  foo = value
+`
+
 const testStateMvNestedModule_stateOutSrc = `
 <no state>
 `