example: Add coap_client example_test

examples/protocols/coap_client/pytest_coap_client_example.py

@@ -0,0 +1,21 @@
+# SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: Unlicense OR CC0-1.0
+import pexpect
+import pytest
+from pytest_embedded import Dut
+
+
+@pytest.mark.esp32
+@pytest.mark.ethernet
+def test_coap_example(dut: Dut) -> None:
+    dut.expect('Loaded app from partition at offset', timeout=30)
+    try:
+        dut.expect(r'IPv4 address: (\d+\.\d+\.\d+\.\d+)[^\d]', timeout=30)
+    except pexpect.exceptions.TIMEOUT:
+        raise ValueError('ENV_TEST_FAILURE: Cannot connect to AP/Ethernet')
+
+    dut.expect('DNS lookup succeeded', timeout=30)
+    dut.expect('Received', timeout=30)
+    dut.expect(r'This server is using the Eclipse Californium \(Cf\) CoAP framework', timeout=30)
+    dut.expect(r'published under EPL\+EDL: http://www\.eclipse\.org/californium/', timeout=30)
+    dut.expect('Starting again!', timeout=30)