device test for #4516 (WiFiClient leaking)

tests/device/test_ClientContext/test_ClientContext.ino

@@ -0,0 +1,95 @@
+#include <Arduino.h>
+#include <BSTest.h>
+#include <test_config.h>
+#include <ESP8266WiFi.h>
+#include <Ticker.h>
+
+extern "C" {
+#include "user_interface.h"
+}
+
+BS_ENV_DECLARE();
+
+// no need for #include
+struct tcp_pcb;
+extern struct tcp_pcb* tcp_tw_pcbs;
+extern "C" void tcp_abort (struct tcp_pcb* pcb);
+
+void tcpCleanup (void)
+{
+  while (tcp_tw_pcbs)
+    tcp_abort(tcp_tw_pcbs);
+}
+
+void setup()
+{
+    Serial.begin(115200);
+    Serial.setDebugOutput(true);
+    WiFi.persistent(false);
+    WiFi.mode(WIFI_STA);
+    WiFi.begin(STA_SSID, STA_PASS);
+    while (WiFi.status() != WL_CONNECTED) {
+        delay(500);
+    }
+    BS_RUN(Serial);
+}
+
+TEST_CASE("WiFi release ClientContext", "[clientcontext]")
+{
+    #define MAXLOOPS       50
+    #define SUCCESS_GOAL 10
+
+    // will search for a tcp server these gateway's ports
+    int ports [] = { 21, 23, 80, 443, 22,
+                     0 };
+    WiFiClient client;
+
+    Serial.print(WiFi.gatewayIP());
+
+    // look for reachable port on gateway
+    int port;
+    for (int i = 0; (port = ports[i]); i++)
+        if (client.connect(WiFi.gatewayIP(), ports[i]))
+        {
+            client.stop();
+            break;
+        }
+
+    Serial.printf(":%d\r\n", port);
+
+    int loops = 0;
+    int success = 0;
+
+    if (port)
+    {
+        tcpCleanup();
+        int heapStart = ESP.getFreeHeap();
+        int minHeap = heapStart / 2;
+        int heap = heapStart;
+        Serial.printf("heap: %d\r\n", heap);
+
+        while (success < SUCCESS_GOAL && ++loops <= MAXLOOPS && (int)ESP.getFreeHeap() > minHeap)
+            if (client.connect(WiFi.gatewayIP(), port))
+            {
+                client.stop();
+                tcpCleanup();
+                int newHeap = (int)ESP.getFreeHeap();
+                Serial.printf("%03d %5d %d\r\n", loops, newHeap, newHeap - heap);
+                if (newHeap - heap == 0)
+                    success++; 
+                heap = newHeap;
+            }
+
+        Serial.printf("heap: %d\r\n"
+                      "loops: %d\r\nstable-loops: %d\r\n",
+            ESP.getFreeHeap(),
+            loops,
+            success);
+    }
+
+    REQUIRE(success >= SUCCESS_GOAL);
+}
+
+void loop()
+{
+}