- Fixed beam search test to use decode

- Enabled it in CI

LLama.Unittest/BeamTests.cs

@@ -27,7 +27,8 @@ public sealed class BeamTests
         _model.Dispose();
     }
 
-    [Fact(Skip = "Very very slow in CI")]
+    //[Fact(Skip = "Very very slow in CI")]
+    [Fact]
     public void BasicBeam()
     {
         const int num_beams = 2;
@@ -36,15 +37,15 @@ public sealed class BeamTests
 
         var context = _model.CreateContext(_params);
 
-        var result = new StringBuilder();
-
         var initial_tokens = context.Tokenize(prompt);
-        result.Append(prompt);
-        //context.Eval(initial_tokens.AsSpan(), 0);
-        throw new NotImplementedException("Replace Eval");
+        var batch = new LLamaBatch();
+        batch.AddRange(initial_tokens, 0, LLamaSeqId.Zero, true);
+        context.Decode(batch);
 
+        var decoder = new StreamingTokenDecoder(context);
         NativeApi.llama_beam_search(context.NativeHandle, (data, state) =>
         {
+            // Show the current state of every beam.
             for (var i = 0; i < state.Beams.Length; i++)
             {
                 ref var view = ref state.Beams[i];
@@ -56,20 +57,17 @@ public sealed class BeamTests
                 _testOutputHelper.WriteLine($"B{i} ({view.CumulativeProbability}) => '{tokens}'");
             }
 
+            // Once all beams agree on some tokens read them and append them to the output decoder
             if (state.CommonPrefixLength > 0)
             {
                 var view = state.Beams[0];
 
-                var decoder = new StreamingTokenDecoder(context);
                 decoder.AddRange(view.Tokens.Slice(0, (int)state.CommonPrefixLength));
-                var tokens = decoder.Read();
-
-                result.Append(tokens);
                 
             }
 
         }, IntPtr.Zero, num_beams, initial_tokens.Length, n_predict, Math.Max(1, Environment.ProcessorCount / 2));
 
-        _testOutputHelper.WriteLine($"Final: {result}");
+        _testOutputHelper.WriteLine($"Final: {prompt}{decoder.Read()}");
     }
 }