add a test case for invalid multi selecT

Author: Emyrk

provider/formtype.go

@@ -127,7 +127,9 @@ func ValidateFormType(paramType OptionType, optionCount int, specifiedFormType P
 		return paramType, specifiedFormType, xerrors.Errorf("value type %q is not supported for 'form_types'", specifiedFormType)
 	}
 
-	// Special case
+	// This is the only current special case. If 'multi-select' is selected, the type
+	// of 'value' and an options 'value' are different. The type of the parameter is
+	// `list(string)` but the type of the individual options is `string`.
 	if paramType == OptionTypeListString && specifiedFormType == ParameterFormTypeMultiSelect {
 		return OptionTypeString, ParameterFormTypeMultiSelect, nil
 	}

provider/formtype_test.go

@@ -220,6 +220,19 @@ func TestValidateFormType(t *testing.T) {
 			optionType: provider.OptionTypeListString,
 			formType:   provider.ParameterFormTypeTagSelect,
 		}),
+
+		// Some manual test cases
+		{
+			name: "list_string_bad_default",
+			config: formTypeCheck{
+				formType:      provider.ParameterFormTypeMultiSelect,
+				optionType:    provider.OptionTypeListString,
+				customOptions: []string{"red", "blue", "green"},
+				defValue:      `["red", "yellow"]`,
+				styling:       nil,
+			},
+			expectError: regexp.MustCompile("is not a valid option"),
+		},
 	}
 
 	t.Run("TabledTests", func(t *testing.T) {

provider/parameter.go

@@ -153,13 +153,17 @@ func parameterDataSource() *schema.Resource {
 			}
 
 			// Validate options
+
+			// optionType might differ from parameter.Type. This is ok, and parameter.Type
+			// should be used for the value type, and optionType for options.
 			var optionType OptionType
 			optionType, parameter.FormType, err = ValidateFormType(parameter.Type, len(parameter.Option), parameter.FormType)
 			if err != nil {
 				return diag.FromErr(err)
 			}
-			// Set the form_type back in case the value was changed, eg via a
-			// default.
+			// Set the form_type back in case the value was changed.
+			// Eg via a default. If a user does not specify, a default value
+			// is used and saved.
 			rd.Set("form_type", parameter.FormType)
 
 			if len(parameter.Option) > 0 {
@@ -187,11 +191,13 @@ func parameterDataSource() *schema.Resource {
 						// If the type is list(string) and optionType is string, we have
 						// to ensure all elements of the default exist as options.
 						var defaultValues []string
+						// TODO: We do this unmarshal in a few spots. It should be standardized.
 						err = json.Unmarshal([]byte(parameter.Default), &defaultValues)
 						if err != nil {
 							return diag.Errorf("default value %q is not a list of strings", parameter.Default)
 						}
 
+						// missing is used to construct a more helpful error message
 						var missing []string
 						for _, defaultValue := range defaultValues {
 							_, defaultIsValid := values[defaultValue]
@@ -206,7 +212,6 @@ func parameterDataSource() *schema.Resource {
 								parameter.Default, strings.Join(missing, ", "),
 							)
 						}
-
 					} else {
 						_, defaultIsValid := values[parameter.Default]
 						if !defaultIsValid {