init: Add godoc comments for `ForceCopy` to mention that it's equivalent to `-migrate-state` in automation (#560)

tfexec/init_test.go

diff --git a/tfexec/init_test.go b/tfexec/init_test.go
index 6f11bab..4e79746 100644
--- a/tfexec/init_test.go
+++ b/tfexec/init_test.go
@@ -48,7 +48,24 @@
 	})
 
 	t.Run("override all defaults", func(t *testing.T) {
-		initCmd, err := tf.initCmd(context.Background(), Backend(false), BackendConfig("confpath1"), BackendConfig("confpath2"), ForceCopy(true), FromModule("testsource"), Get(false), GetPlugins(false), Lock(false), LockTimeout("999s"), PluginDir("testdir1"), PluginDir("testdir2"), Reconfigure(true), Upgrade(true), VerifyPlugins(false), Dir("initdir"))
+		initCmd, err := tf.initCmd(
+			context.Background(),
+			FromModule("testsource"),
+			LockTimeout("999s"),
+			Backend(false),
+			Get(false),
+			Upgrade(true),
+			Lock(false),
+			GetPlugins(false),
+			VerifyPlugins(false),
+			ForceCopy(true),
+			Reconfigure(true),
+			BackendConfig("confpath1"),
+			BackendConfig("confpath2"),
+			PluginDir("testdir1"),
+			PluginDir("testdir2"),
+			Dir("initdir"),
+		)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -105,7 +122,20 @@
 	})
 
 	t.Run("override all defaults", func(t *testing.T) {
-		initCmd, err := tf.initCmd(context.Background(), Backend(false), BackendConfig("confpath1"), BackendConfig("confpath2"), FromModule("testsource"), Get(false), PluginDir("testdir1"), PluginDir("testdir2"), Reconfigure(true), Upgrade(true), Dir("initdir"))
+		initCmd, err := tf.initCmd(
+			context.Background(),
+			FromModule("testsource"),
+			Backend(false),
+			Get(false),
+			Upgrade(true),
+			ForceCopy(true),
+			Reconfigure(true),
+			BackendConfig("confpath1"),
+			BackendConfig("confpath2"),
+			PluginDir("testdir1"),
+			PluginDir("testdir2"),
+			Dir("initdir"),
+		)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -118,6 +148,7 @@
 			"-backend=false",
 			"-get=false",
 			"-upgrade=true",
+			"-force-copy",
 			"-reconfigure",
 			"-backend-config=confpath1",
 			"-backend-config=confpath2",
@@ -158,7 +189,20 @@
 	})
 
 	t.Run("override all defaults", func(t *testing.T) {
-		initCmd, err := tf.initJSONCmd(context.Background(), Backend(false), BackendConfig("confpath1"), BackendConfig("confpath2"), FromModule("testsource"), Get(false), PluginDir("testdir1"), PluginDir("testdir2"), Reconfigure(true), Upgrade(true), Dir("initdir"))
+		initCmd, err := tf.initJSONCmd(
+			context.Background(),
+			FromModule("testsource"),
+			Backend(false),
+			Get(false),
+			Upgrade(true),
+			ForceCopy(true),
+			Reconfigure(true),
+			BackendConfig("confpath1"),
+			BackendConfig("confpath2"),
+			PluginDir("testdir1"),
+			PluginDir("testdir2"),
+			Dir("initdir"),
+		)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -171,6 +215,7 @@
 			"-backend=false",
 			"-get=false",
 			"-upgrade=true",
+			"-force-copy",
 			"-reconfigure",
 			"-backend-config=confpath1",
 			"-backend-config=confpath2",

tfexec/options.go

diff --git a/tfexec/options.go b/tfexec/options.go
index 85d2acd..145f10a 100644
--- a/tfexec/options.go
+++ b/tfexec/options.go
@@ -168,10 +168,18 @@
 	return &ForceOption{force}
 }
 
+// ForceCopyOption represents the `-force-copy` flag for `terraform init`.
+// Defaults to false.
 type ForceCopyOption struct {
 	forceCopy bool
 }
 
+// ForceCopy returns a ForceCopyOption that indicates whether the init command's -force-copy flag
+// should be set to true or false.
+//
+// Using -force-copy with an init command enables the -migrate-state option but all prompts for
+// input are suppressed and automatically answers "yes" to the migration questions. This is an
+// alternative to `-migrate-state` when Terraform is running in automation, including via terrform-exec.
 func ForceCopy(forceCopy bool) *ForceCopyOption {
 	return &ForceCopyOption{forceCopy}
 }

tfexec/version.go

diff --git a/tfexec/version.go b/tfexec/version.go
index cbf28fb..5745ea9 100644
--- a/tfexec/version.go
+++ b/tfexec/version.go
@@ -22,6 +22,7 @@
 	tf0_6_13 = version.Must(version.NewVersion("0.6.13"))
 	tf0_7_7  = version.Must(version.NewVersion("0.7.7"))
 	tf0_8_0  = version.Must(version.NewVersion("0.8.0"))
+	tf0_9_2  = version.Must(version.NewVersion("0.9.2"))
 	tf0_10_0 = version.Must(version.NewVersion("0.10.0"))
 	tf0_12_0 = version.Must(version.NewVersion("0.12.0"))
 	tf0_13_0 = version.Must(version.NewVersion("0.13.0"))