Tests: get rid of classes in test files.

Class usage came from the unittest framework and it was always redundant
after migration to the pytest.  This commit removes classes from files
containing tests to make them more readable and understandable.

test/test_node_es_modules.py

@@ -1,46 +1,48 @@
 from packaging import version
-from unit.applications.lang.node import TestApplicationNode
-from unit.applications.websockets import TestApplicationWebsocket
+from unit.applications.lang.node import ApplicationNode
+from unit.applications.websockets import ApplicationWebsocket
 
 prerequisites = {
     'modules': {'node': lambda v: version.parse(v) >= version.parse('14.16.0')}
 }
 
+client = ApplicationNode(es_modules=True)
+ws = ApplicationWebsocket()
 
-class TestNodeESModules(TestApplicationNode):
-    es_modules = True
-    ws = TestApplicationWebsocket()
 
-    def assert_basic_application(self):
-        resp = self.get()
-        assert resp['headers']['Content-Type'] == 'text/plain', 'basic header'
-        assert resp['body'] == 'Hello World\n', 'basic body'
+def assert_basic_application():
+    resp = client.get()
+    assert resp['headers']['Content-Type'] == 'text/plain', 'basic header'
+    assert resp['body'] == 'Hello World\n', 'basic body'
 
-    def test_node_es_modules_loader_http(self):
-        self.load('loader/es_modules_http', name="app.mjs")
 
-        self.assert_basic_application()
+def test_node_es_modules_loader_http():
+    client.load('loader/es_modules_http', name="app.mjs")
 
-    def test_node_es_modules_loader_http_indirect(self):
-        self.load('loader/es_modules_http_indirect', name="app.js")
+    assert_basic_application()
 
-        self.assert_basic_application()
 
-    def test_node_es_modules_loader_websockets(self):
-        self.load('loader/es_modules_websocket', name="app.mjs")
+def test_node_es_modules_loader_http_indirect():
+    client.load('loader/es_modules_http_indirect', name="app.js")
 
-        message = 'blah'
+    assert_basic_application()
 
-        _, sock, _ = self.ws.upgrade()
 
-        self.ws.frame_write(sock, self.ws.OP_TEXT, message)
-        frame = self.ws.frame_read(sock)
+def test_node_es_modules_loader_websockets():
+    client.load('loader/es_modules_websocket', name="app.mjs")
 
-        assert message == frame['data'].decode('utf-8'), 'mirror'
+    message = 'blah'
 
-        self.ws.frame_write(sock, self.ws.OP_TEXT, message)
-        frame = self.ws.frame_read(sock)
+    _, sock, _ = ws.upgrade()
 
-        assert message == frame['data'].decode('utf-8'), 'mirror 2'
+    ws.frame_write(sock, ws.OP_TEXT, message)
+    frame = ws.frame_read(sock)
 
-        sock.close()
+    assert message == frame['data'].decode('utf-8'), 'mirror'
+
+    ws.frame_write(sock, ws.OP_TEXT, message)
+    frame = ws.frame_read(sock)
+
+    assert message == frame['data'].decode('utf-8'), 'mirror 2'
+
+    sock.close()