tests/net_inet: Add tests for accept and connect in nonblocking mode.

Some of these tests don't require an Internet connection, but here is a
good place to put them for now.

tests/net_inet/accept_nonblock.py

@@ -0,0 +1,16 @@
+# test that socket.accept() on a non-blocking socket raises EAGAIN
+
+try:
+    import usocket as socket
+except:
+    import socket
+
+s = socket.socket()
+s.bind(socket.getaddrinfo('127.0.0.1', 8123)[0][-1])
+s.setblocking(False)
+s.listen(1)
+try:
+    s.accept()
+except OSError as er:
+    print(er.args[0] == 11) # 11 is EAGAIN
+s.close()

tests/net_inet/accept_nonblock.py.exp

@@ -0,0 +1 @@
+True

tests/net_inet/accept_timeout.py

@@ -0,0 +1,22 @@
+# test that socket.accept() on a socket with timeout raises ETIMEDOUT
+
+try:
+    import usocket as socket
+except:
+    import socket
+
+try:
+    socket.socket.settimeout
+except AttributeError:
+    print('SKIP')
+    raise SystemExit
+
+s = socket.socket()
+s.bind(socket.getaddrinfo('127.0.0.1', 8123)[0][-1])
+s.settimeout(1)
+s.listen(1)
+try:
+    s.accept()
+except OSError as er:
+    print(er.args[0] in (110, 'timed out')) # 110 is ETIMEDOUT; CPython uses a string
+s.close()

tests/net_inet/accept_timeout.py.exp

@@ -0,0 +1 @@
+True

tests/net_inet/connect_nonblock.py

@@ -0,0 +1,14 @@
+# test that socket.connect() on a non-blocking socket raises EINPROGRESS
+
+try:
+    import usocket as socket
+except:
+    import socket
+
+s = socket.socket()
+s.setblocking(False)
+try:
+    s.connect(socket.getaddrinfo('micropython.org', 80)[0][-1])
+except OSError as er:
+    print(er.args[0] == 115) # 115 is EINPROGRESS
+s.close()

tests/net_inet/connect_nonblock.py.exp

@@ -0,0 +1 @@
+True