Test case for changing backend hash during aborted state migration

Pulled and updated from
https://github.com/hashicorp/terraform/pull/26260

internal/command/init_test.go

@@ -616,6 +616,41 @@ func TestInit_backendMigrateWhileLocked(t *testing.T) {
 	}
 }
 
+func TestInit_backendConfigFileChangeWithExistingState(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	testCopyDir(t, testFixturePath("init-backend-config-file-change-migrate-existing"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+	}
+
+	oldState := testDataStateRead(t, filepath.Join(DefaultDataDir, DefaultStateFilename))
+
+	// we deliberately do not provide the answer for backend-migrate-copy-to-empty to trigger error
+	args := []string{"-migrate-state", "-backend-config", "input.config", "-input=true"}
+	if code := c.Run(args); code == 0 {
+		t.Fatal("expected error")
+	}
+
+	// Read our backend config and verify new settings are not saved
+	state := testDataStateRead(t, filepath.Join(DefaultDataDir, DefaultStateFilename))
+	if got, want := normalizeJSON(t, state.Backend.ConfigRaw), `{"path":"local-state.tfstate"}`; got != want {
+		t.Errorf("wrong config\ngot:  %s\nwant: %s", got, want)
+	}
+
+	// without changing config, hash should not change
+	if oldState.Backend.Hash != state.Backend.Hash {
+		t.Errorf("backend hash should not have changed\ngot:  %d\nwant: %d", state.Backend.Hash, oldState.Backend.Hash)
+	}
+}
+
 func TestInit_backendConfigKV(t *testing.T) {
 	// Create a temporary working directory that is empty
 	td := tempDir(t)

internal/command/testdata/init-backend-config-file-change-migrate-existing/.terraform/terraform.tfstate

@@ -0,0 +1,22 @@
+{
+    "version": 3,
+    "serial": 0,
+    "lineage": "666f9301-7e65-4b19-ae23-71184bb19b03",
+    "backend": {
+        "type": "local",
+        "config": {
+            "path": "local-state.tfstate"
+        },
+        "hash": 9073424445967744180
+    },
+    "modules": [
+        {
+            "path": [
+                "root"
+            ],
+            "outputs": {},
+            "resources": {},
+            "depends_on": []
+        }
+    ]
+}

internal/command/testdata/init-backend-config-file-change-migrate-existing/input.config

@@ -0,0 +1 @@
+path = "hello"

internal/command/testdata/init-backend-config-file-change-migrate-existing/local-state.tfstate

@@ -0,0 +1,21 @@
+{
+    "version": 3,
+    "terraform_version": "0.8.2",
+    "serial": 8,
+    "lineage": "local",
+    "modules": [
+        {
+            "path": [
+                "root"
+            ],
+            "outputs": {
+                "foo": {
+                    "type": "string",
+                    "value": "bar"
+                }
+            },
+            "resources": {},
+            "depends_on": []
+        }
+    ]
+}

internal/command/testdata/init-backend-config-file-change-migrate-existing/main.tf

@@ -0,0 +1,5 @@
+terraform {
+    backend "local" {
+        path = "local-state.tfstate"
+    }
+}