add some shape test cases to have better coverage

src/include/migraphx/op/broadcast.hpp

@@ -47,14 +47,14 @@ struct broadcast
                broadcast_lens.cbegin(), broadcast_lens.cend(), [&](auto x) { return x == 1; }))
         {
             if(axis != 0)
-                MIGRAPHX_THROW("when broadcasting tensor of size 1, axis should be 0");
+                MIGRAPHX_THROW("BROADCAST: when broadcasting tensor of size 1, axis should be 0");
             return {t, broadcast_lens, std::move(bcast_strides)};
         }
         else
         {
             assert(broadcast_lens.size() - axis >= input.lens().size());
             if(!std::equal(input.lens().begin(), input.lens().end(), broadcast_lens.begin() + axis))
-                MIGRAPHX_THROW("when broadcasting success sizes must match");
+                MIGRAPHX_THROW("BROADCAST: when broadcasting success sizes must match");
             std::copy(input.strides().begin(), input.strides().end(), bcast_strides.begin() + axis);
             return {t, broadcast_lens, std::move(bcast_strides)};
         }

test/op_shape_test.cpp

@@ -229,6 +229,38 @@ TEST_CASE(multibroadcast)
     }
 }
 
+TEST_CASE(broadcast)
+{
+    {
+        std::vector<std::size_t> lens{1, 1};
+        migraphx::shape input{migraphx::shape::float_type, {4, 1, 3}};
+        expect_shape(migraphx::shape{migraphx::shape::float_type, {1, 1}, {0, 0}},
+                     migraphx::op::broadcast{0, lens},
+                     input);
+    }
+    {
+        std::vector<std::size_t> lens{1, 1};
+        migraphx::shape input{migraphx::shape::float_type, {4, 1, 3}};
+        throws_shape(migraphx::op::broadcast{1, lens},
+                     input);
+    }
+
+    {
+        std::vector<std::size_t> lens{3, 2, 4, 3};
+        migraphx::shape input{migraphx::shape::float_type, {4, 3}};
+        expect_shape(migraphx::shape{migraphx::shape::float_type, {3, 2, 4, 3}, {0, 0, 3, 1}},
+                     migraphx::op::broadcast{2, lens},
+                     input);
+    }
+
+    {
+        std::vector<std::size_t> lens{3, 2, 4, 3};
+        migraphx::shape input{migraphx::shape::float_type, {4, 4}};
+        throws_shape(migraphx::op::broadcast{2, lens},
+                     input);
+    }
+}
+
 TEST_CASE(gather)
 {
     {