[ML] Fixing failing inference api streaming tests (#118284) (#118797)

* Fixing tests with alphanumeric strings

* Removing prints

(cherry picked from commit dcae87d)

# Conflicts:
#	muted-tests.yml

Author: jonathan-buttner

test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java

@@ -275,6 +275,11 @@ public static void resetPortCounter() {
 
     private static final SetOnce<Boolean> WARN_SECURE_RANDOM_FIPS_NOT_DETERMINISTIC = new SetOnce<>();
 
+    private static final String LOWER_ALPHA_CHARACTERS = "abcdefghijklmnopqrstuvwxyz";
+    private static final String UPPER_ALPHA_CHARACTERS = LOWER_ALPHA_CHARACTERS.toUpperCase(Locale.ROOT);
+    private static final String DIGIT_CHARACTERS = "0123456789";
+    private static final String ALPHANUMERIC_CHARACTERS = LOWER_ALPHA_CHARACTERS + UPPER_ALPHA_CHARACTERS + DIGIT_CHARACTERS;
+
     static {
         Random random = initTestSeed();
         TEST_WORKER_VM_ID = System.getProperty(TEST_WORKER_SYS_PROPERTY, DEFAULT_TEST_WORKER_ID);
@@ -1195,6 +1200,21 @@ public static String randomAlphaOfLength(int codeUnits) {
         return RandomizedTest.randomAsciiOfLength(codeUnits);
     }
 
+    /**
+     * Generate a random string containing only alphanumeric characters.
+     * @param length the length of the string to generate
+     * @return the generated string
+     */
+    public static String randomAlphanumericOfLength(int length) {
+        StringBuilder sb = new StringBuilder();
+        Random random = random();
+        for (int i = 0; i < length; i++) {
+            sb.append(ALPHANUMERIC_CHARACTERS.charAt(random.nextInt(ALPHANUMERIC_CHARACTERS.length())));
+        }
+
+        return sb.toString();
+    }
+
     public static SecureString randomSecureStringOfLength(int codeUnits) {
         var randomAlpha = randomAlphaOfLength(codeUnits);
         return new SecureString(randomAlpha.toCharArray());

x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/InferenceCrudIT.java

@@ -312,7 +312,7 @@ public void testSupportedStream() throws Exception {
         assertEquals(modelId, singleModel.get("inference_id"));
         assertEquals(TaskType.COMPLETION.toString(), singleModel.get("task_type"));
 
-        var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomUUID()).toList();
+        var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomAlphanumericOfLength(5)).toList();
         try {
             var events = streamInferOnMockService(modelId, TaskType.COMPLETION, input);
 
@@ -339,7 +339,7 @@ public void testUnifiedCompletionInference() throws Exception {
         assertEquals(modelId, singleModel.get("inference_id"));
         assertEquals(TaskType.COMPLETION.toString(), singleModel.get("task_type"));
 
-        var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomUUID()).toList();
+        var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomAlphanumericOfLength(5)).toList();
         try {
             var events = unifiedCompletionInferOnMockService(modelId, TaskType.COMPLETION, input);
             var expectedResponses = expectedResultsIterator(input);