add unit test for issue1356 (project-chip#1384)

src-electron/generator/helper-endpointconfig.js

@@ -833,15 +833,7 @@ async function collectAttributes(db, sessionId, endpointTypes, options) {
             attributeDefaultValue === null &&
             a.isNullable
           ) {
-            // We don't want to make longTypeDefaultValue know about our null
-            // string representation.
-            if (types.isOneBytePrefixedString(a.type)) {
-              def = '0xFF,'
-            } else if (types.isTwoBytePrefixedString(a.type)) {
-              def = '0xFF, 0xFF,'
-            } else {
-              throw new Error(`Unknown string type: ${type}`)
-            }
+            def = types.nullStringDefaultValue(a.type)
           } else {
             def = types.longTypeDefaultValue(
               defaultSize,

src-electron/util/types.js

@@ -311,6 +311,31 @@ function isTwoBytePrefixedString(type) {
   return type == 'long_char_string' || type == 'long_octet_string'
 }
 
+/**
+ * Generates a default value for a null string based on its type.
+ * This function is designed to abstract away the specific null representation
+ * of strings from the longTypeDefaultValue function, ensuring that the latter
+ * does not need to be aware of these details.
+ *
+ * @param {string} type - The type of the string, which determines its null representation.
+ * @returns {string} The default value for a null string of the specified type.
+ * @throws {Error} Throws an error if the string type is unknown.
+ */
+
+function nullStringDefaultValue(type) {
+  // We don't want to make longTypeDefaultValue know about our null
+  // string representation.
+  let def
+  if (isOneBytePrefixedString(type)) {
+    def = '0xFF,'
+  } else if (isTwoBytePrefixedString(type)) {
+    def = '0xFF, 0xFF,'
+  } else {
+    throw new Error(`Unknown string type: ${type}`)
+  }
+  return def
+}
+
 /**
  * Given a zcl device type returns its sign, size and zcl data type info stored
  * in the database table.
@@ -420,3 +445,4 @@ exports.convertFloatToBigEndian = convertFloatToBigEndian
 exports.getSignAndSizeOfZclType = getSignAndSizeOfZclType
 exports.intToHexString = intToHexString
 exports.hexStringToInt = hexStringToInt
+exports.nullStringDefaultValue = nullStringDefaultValue

test/types.test.js

@@ -0,0 +1,15 @@
+const types = require('../src-electron/util/types')
+const env = require('../src-electron/util/env')
+
+beforeAll(() => {
+  env.setDevelopmentEnv()
+})
+
+test('ZCL types nullable strings', () => {
+  let r
+  r = types.nullStringDefaultValue('char_string')
+  expect(r).toContain('0xFF,')
+
+  r = types.nullStringDefaultValue('long_char_string')
+  expect(r).toContain('0xFF, 0xFF,')
+})