test: fix DimensionMismatch for triangular

Author: inkydragon

test/triangular.jl

@@ -904,12 +904,12 @@ end
         A = UpperTriangular(ones(T,2,2))
         B = ones(T,3,3)
         C = similar(B)
-        @test_throws "incompatible dimensions for matrix multiplication" mul!(C, A, B)
-        @test_throws "incompatible dimensions for matrix multiplication" mul!(C, B, A)
+        @test_throws DimensionMismatch mul!(C, A, B)
+        @test_throws DimensionMismatch mul!(C, B, A)
         B = Array(A)
         C = similar(B, (4,4))
-        @test_throws "incompatible destination size" mul!(C, A, B)
-        @test_throws "incompatible destination size" mul!(C, B, A)
+        @test_throws DimensionMismatch mul!(C, A, B)
+        @test_throws DimensionMismatch mul!(C, B, A)
     end
 end