Use 2D shapes in MatMulInteger regression tests

ONNX MatMulInteger spec requires 2D+ inputs, so 1D shapes were rejected
at model validation time before reaching our kernel fix. Changed tests
to use 2D shapes that still validate the K-dimension mismatch check.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bmehta001

onnxruntime/test/providers/cpu/math/matmul_integer_test.cc

@@ -504,28 +504,33 @@ TEST(MatmulIntegerOpTest, SharedPrepackedWeights) {
 }
 #endif
 
-// Regression test: 1D inputs with mismatched K dimensions must fail
+// Regression test: inputs with mismatched K dimensions must fail
 // instead of causing an out-of-bounds read in the MLAS backend.
-TEST(MatmulIntegerOpTest, MatMulInteger_1D_DimensionMismatch) {
+TEST(MatmulIntegerOpTest, MatMulInteger_DimensionMismatch) {
   OpTester test("MatMulInteger", 10);
-  // A is 1D with K=5, B is 1D with K=1 — dimensions don't match.
-  test.AddInput<uint8_t>("T1", {5}, {11, 7, 3, 10, 6});
-  test.AddInput<uint8_t>("T2", {1}, {1});
+  // A is [1,5] (K=5), B is [1,1] (K=1) — K dimensions don't match.
+  test.AddInput<uint8_t>("T1", {1, 5}, {11, 7, 3, 10, 6});
+  test.AddInput<uint8_t>("T2", {1, 1}, {1});
   test.AddInput<uint8_t>("a_zero_point", {}, {0});
   test.AddInput<uint8_t>("b_zero_point", {}, {0});
-  test.AddOutput<int32_t>("T3", {}, {0});
-  test.Run(OpTester::ExpectResult::kExpectFailure, "MatMul dimension mismatch");
+  test.AddOutput<int32_t>("T3", {1, 1}, {0});
+
+  // Restrict to CPU — other EPs may not support this configuration.
+  std::vector<std::unique_ptr<IExecutionProvider>> cpu_only;
+  cpu_only.push_back(DefaultCpuExecutionProvider());
+  test.Run(OpTester::ExpectResult::kExpectFailure, "MatMul dimension mismatch",
+           {}, nullptr, &cpu_only);
 }
 
-// Valid 1D × 1D dot product: both vectors have the same K.
-TEST(MatmulIntegerOpTest, MatMulInteger_1D_Valid) {
+// Valid 2D dot product: K dimensions match.
+TEST(MatmulIntegerOpTest, MatMulInteger_SmallValid) {
   OpTester test("MatMulInteger", 10);
-  // A=[2,3], B=[4,5] => dot = 2*4 + 3*5 = 23
-  test.AddInput<uint8_t>("T1", {2}, {2, 3});
-  test.AddInput<uint8_t>("T2", {2}, {4, 5});
+  // A=[1,2], B=[2,1] => [1,1] with value 2*4 + 3*5 = 23
+  test.AddInput<uint8_t>("T1", {1, 2}, {2, 3});
+  test.AddInput<uint8_t>("T2", {2, 1}, {4, 5});
   test.AddInput<uint8_t>("a_zero_point", {}, {0});
   test.AddInput<uint8_t>("b_zero_point", {}, {0});
-  test.AddOutput<int32_t>("T3", {}, {23});
+  test.AddOutput<int32_t>("T3", {1, 1}, {23});
   test.Run();
 }