chore: add test from #665

Author: ansgarm

hclsyntax/expression_template_test.go

@@ -438,6 +438,28 @@ trim`,
 
 }
 
+func TestTemplateExprGracefulValue(t *testing.T) {
+	// we don't care about diags since we know it's invalid config
+	expr, _ := ParseTemplate([]byte(`prefix${provider::}`), "", hcl.Pos{Line: 1, Column: 1, Byte: 0})
+
+	got, _ := expr.Value(nil) // this should not panic
+
+	if !got.RawEquals(cty.UnknownVal(cty.String).RefineNotNull()) {
+		t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, cty.UnknownVal(cty.String).RefineNotNull())
+	}
+}
+
+func TestTemplateExprWrappedGracefulValue(t *testing.T) {
+	// we don't care about diags since we know it's invalid config
+	expr, _ := ParseTemplate([]byte(`${provider::}`), "", hcl.Pos{Line: 1, Column: 1, Byte: 0})
+
+	got, _ := expr.Value(nil) // this should not panic
+
+	if !got.RawEquals(cty.DynamicVal) {
+		t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, cty.NilVal)
+	}
+}
+
 func TestTemplateExprIsStringLiteral(t *testing.T) {
 	tests := map[string]bool{
 		// A simple string value is a string literal