additional tests

stdlib/LinearAlgebra/test/matmul.jl

@@ -157,15 +157,55 @@ end
 end
 
 @testset "generic_matvecmul for vectors of vectors" begin
-    u = [[1, 2], [3, 4]]
+    @testset "matrix of scalars" begin
+        u = [[1, 2], [3, 4]]
+        A = [1 2; 3 4]
+        v = [[0, 0], [0, 0]]
+        Au = [[7, 10], [15, 22]]
+        @test A * u == Au
+        mul!(v, A, u)
+        @test v == Au
+        mul!(v, A, u, 2, -1)
+        @test v == Au
+    end
+
+    @testset "matrix of matrices" begin
+        u = [[1, 2], [3, 4]]
+        A = Matrix{Matrix{Int}}(undef, 2, 2)
+        A[1, 1] = [1 2; 3 4]
+        A[1, 2] = [5 6; 7 8]
+        A[2, 1] = [9 10; 11 12]
+        A[2, 2] = [13 14; 15 16]
+        v = [[0, 0], [0, 0]]
+        Au = [[44, 64], [124, 144]]
+        @test A * u == Au
+        mul!(v, A, u)
+        @test v == Au
+        mul!(v, A, u, 2, -1)
+        @test v == Au
+    end
+end
+
+@testset "generic_matmatmul for matrices of vectors" begin
+    B = Matrix{Vector{Int}}(undef, 2, 2)
+    B[1, 1] = [1, 2]
+    B[2, 1] = [3, 4]
+    B[1, 2] = [5, 6]
+    B[2, 2] = [7, 8]
     A = [1 2; 3 4]
-    v = [[0, 0], [0, 0]]
-    Au = [[7, 10], [15, 22]]
-    @test A * u == Au
-    mul!(v, A, u)
-    @test v == Au
-    mul!(v, A, u, 2, 1)
-    @test v == [[15, 22], [33, 48]]
+    C = Matrix{Vector{Int}}(undef, 2, 2)
+    AB = Matrix{Vector{Int}}(undef, 2, 2)
+    AB[1, 1] = [7, 10]
+    AB[2, 1] = [15, 22]
+    AB[1, 2] = [19, 22]
+    AB[2, 2] = [43, 50]
+    @test A * B == AB
+    mul!(C, A, B)
+    @test C == AB
+    mul!(C, A, B, 2, -1)
+    @test C == AB
+    LinearAlgebra._generic_matmatmul!(C, 'N', 'N', A, B, LinearAlgebra.MulAddMul(2, -1))
+    @test C == AB
 end
 
 @testset "fallbacks & such for BlasFloats" begin