Make HPACK encoding test deterministic

java/org/apache/coyote/http2/HpackEncoder.java

@@ -109,7 +109,11 @@ public boolean shouldUseHuffman(String header) {
     private final HpackHeaderFunction hpackHeaderFunction;
 
     HpackEncoder() {
-        this.hpackHeaderFunction = DEFAULT_HEADER_FUNCTION;
+        this(DEFAULT_HEADER_FUNCTION);
+    }
+
+    HpackEncoder(HpackHeaderFunction hpackHeaderFunction) {
+        this.hpackHeaderFunction = hpackHeaderFunction;
     }
 
     /**
@@ -398,7 +402,7 @@ int getPosition() {
         }
     }
 
-    private interface HpackHeaderFunction {
+    interface HpackHeaderFunction {
         boolean shouldUseIndexing(String header, String value);
 
         /**

test/org/apache/coyote/http2/TestHpack.java

@@ -32,11 +32,26 @@ public void testEncode() throws Exception {
         headers.setValue(":status").setString("200");
         headers.setValue("header2").setString("value2");
         ByteBuffer output = ByteBuffer.allocate(512);
-        HpackEncoder encoder = new HpackEncoder();
+        HpackEncoder encoder = new HpackEncoder(new HpackEncoder.HpackHeaderFunction() {
+
+            @Override
+            public boolean shouldUseIndexing(String header, String value) {
+                return true;
+            }
+
+            @Override
+            public boolean shouldUseHuffman(String header, String value) {
+                return true;
+            }
+
+            @Override
+            public boolean shouldUseHuffman(String header) {
+                return true;
+            }
+        });
         encoder.encode(headers, output);
         output.flip();
-        // Size is supposed to be 33 without huffman, or 27 with it
-        // TODO: use the HpackHeaderFunction to enable huffman predictably
+        // Size is 27 with Huffman encoding
         Assert.assertEquals(27, output.remaining());
         output.clear();
         encoder.encode(headers, output);