diff --git a/backend/remote-state/gcloud/backend_test.go b/backend/remote-state/gcloud/backend_test.go
new file mode 100644
index 0000000000..c86a5375fb
--- /dev/null
+++ b/backend/remote-state/gcloud/backend_test.go
@@ -0,0 +1,36 @@
+package gcloud
+
+import (
+	"testing"
+)
+
+func TestStateFile(t *testing.T) {
+	cases := []struct {
+		stateDir         string
+		defaultStateFile string
+		name             string
+		wantStateFile    string
+		wantLockFile     string
+	}{
+		{"state", "", "default", "state/default.tfstate", "state/default.tflock"},
+		{"state", "", "test", "state/test.tfstate", "state/test.tflock"},
+		{"state", "legacy.tfstate", "default", "legacy.tfstate", "legacy.tflock"},
+		{"state", "legacy.tfstate", "test", "state/test.tfstate", "state/test.tflock"},
+		{"state", "legacy.state", "default", "legacy.state", "legacy.state.tflock"},
+		{"state", "legacy.state", "test", "state/test.tfstate", "state/test.tflock"},
+	}
+	for _, c := range cases {
+		b := &gcsBackend{
+			stateDir:         c.stateDir,
+			defaultStateFile: c.defaultStateFile,
+		}
+
+		if got := b.stateFile(c.name); got != c.wantStateFile {
+			t.Errorf("stateFile(%q) = %q, want %q", c.name, got, c.wantStateFile)
+		}
+
+		if got := b.lockFile(c.name); got != c.wantLockFile {
+			t.Errorf("lockFile(%q) = %q, want %q", c.name, got, c.wantLockFile)
+		}
+	}
+}