Add unit test for HEAD request and fix for checking the content length of a HEAD response

Author: jentfoo

client/src/main/java/org/threadly/litesockets/client/http/HTTPClient.java

@@ -594,7 +594,12 @@ public HTTPResponseCode getResponseCode() {
     }
 
     public long getContentLength() {
-      return body.remaining();
+      long result = hr.getHeaders().getContentLength();
+      if (result >= 0) {
+        return result;
+      } else {
+        return body.remaining();
+      }
     }
 
     public MergedByteBuffers getBody() {

client/src/test/java/org/threadly/litesockets/client/http/HTTPClientTests.java

@@ -291,6 +291,21 @@ public void noContentLengthWithBody() throws IOException, HTTPParsingException {
     assertEquals("TEST123", hrs.getBodyAsString());
   }
 
+  @Test
+  public void contentLengthOnHeadRequest() throws IOException, HTTPParsingException {
+    int port = PortUtils.findTCPPort(); // TODO
+    fakeServer = new TestHTTPServer(port, RESPONSE_CL, "", false, true);
+    final HTTPRequestBuilder hrb = new HTTPRequestBuilder(new URL("http://localhost:"+port));
+    hrb.setRequestMethod("HEAD");
+    
+    final HTTPClient httpClient = new HTTPClient();
+    httpClient.start();
+    HTTPResponseData hrs = httpClient.request(hrb.buildClientHTTPRequest());
+    System.out.println(hrs.getResponse());
+    assertEquals(CONTENT.length(), hrs.getContentLength());
+    assertEquals("", hrs.getBodyAsString());
+  }
+
   @Test
   public void closeBeforeLength() throws IOException, HTTPParsingException {
     int port = PortUtils.findTCPPort();