@Test public void supportedExtensions() { WebSocketExtension extension1 = new WebSocketExtension("ext1"); WebSocketExtension extension2 = new WebSocketExtension("ext2"); given(this.upgradeStrategy.getSupportedVersions()).willReturn(new String[] {"13"}); given(this.upgradeStrategy.getSupportedExtensions(this.request)).willReturn(Collections.singletonList(extension1)); this.servletRequest.setMethod("GET"); WebSocketHttpHeaders headers = new WebSocketHttpHeaders(this.request.getHeaders()); headers.setUpgrade("WebSocket"); headers.setConnection("Upgrade"); headers.setSecWebSocketVersion("13"); headers.setSecWebSocketKey("82/ZS2YHjEnUN97HLL8tbw=="); headers.setSecWebSocketExtensions(Arrays.asList(extension1, extension2)); WebSocketHandler handler = new TextWebSocketHandler(); Map<String, Object> attributes = Collections.<String, Object>emptyMap(); this.handshakeHandler.doHandshake(this.request, this.response, handler, attributes); verify(this.upgradeStrategy).upgrade(this.request, this.response, null, Collections.singletonList(extension1), null, handler, attributes); }