Add UT to cover the changes

Author: HectorSVC

onnxruntime/test/contrib_ops/matmul_2bits_test.cc

@@ -540,6 +540,49 @@ TEST(MatMul2BitsWebGpu, Float32_ZeroPoint_LargerK) {
   RunWebGpu2BitsTest<float>(1, 32, 256, 32, true, 0.3f, 0.05f);
 }
 
+// DP4A path tests (accuracy_level=4) — exercises the 1024-entry LUT / dequantization
+// path for 2-bit weights with zero_points.
+// DP4A constraints: accuracy_level==4, block_size%32==0, K%128==0, N%16==0.
+TEST(MatMul2BitsWebGpu, Float32_ZeroPoint_DP4A) {
+  TestOptions2Bits opts{};
+  opts.accuracy_level = 4;
+  opts.has_zero_point = true;
+  opts.output_abs_error = 0.1f;
+  opts.output_rel_error = 0.02f;
+
+  // M=1, N=16, K=128, block_size=32 — minimal DP4A-eligible shape
+  opts.M = 1;
+  opts.N = 16;
+  opts.K = 128;
+  opts.block_size = 32;
+  RunTest2Bits<float>(opts);
+
+  // M=1, N=32, K=256, block_size=32 — larger K
+  opts.M = 1;
+  opts.N = 32;
+  opts.K = 256;
+  opts.block_size = 32;
+  opts.output_abs_error = 0.3f;
+  opts.output_rel_error = 0.05f;
+  RunTest2Bits<float>(opts);
+
+  // M=4 (batch), N=32, K=128, block_size=32
+  opts.M = 4;
+  opts.N = 32;
+  opts.K = 128;
+  opts.block_size = 32;
+  opts.output_abs_error = 0.1f;
+  opts.output_rel_error = 0.02f;
+  RunTest2Bits<float>(opts);
+
+  // M=1, N=16, K=128, block_size=128 — full-block
+  opts.M = 1;
+  opts.N = 16;
+  opts.K = 128;
+  opts.block_size = 128;
+  RunTest2Bits<float>(opts);
+}
+
 #endif  // USE_WEBGPU
 
 }  // namespace test