set.seed(20250409)

covprod <- distfreereg:::covprod

block_dims <- c(7,5,13)
n <- sum(block_dims)

Sigma_list <- lapply(seq_along(block_dims),
                     function(i) rWishart(1, df = block_dims[i], diag(block_dims[i]))[,,1])

Sigma_mat <- as.matrix(Matrix::bdiag(Sigma_list))
Sigma_vec <- rnorm(n)
Sigma_num <- rnorm(1)
M <- matrix(rnorm(3*n), nrow = n)

all.equal(covprod(Sigma_list, M),
          Sigma_mat %*% M)
all.equal(covprod(Sigma_mat, M),
          Sigma_mat %*% M)
all.equal(covprod(Sigma_vec, M),
          diag(Sigma_vec) %*% M)
all.equal(covprod(Sigma_num, M),
          diag(Sigma_num, nrow = n) %*% M)