[R] merging tables based on both row and column names

[C Lin]

Dear R users,

I am trying to merge tables based on both their row names and column names.
My ultimate goal is to build a distribution table of values for each combination of row and column names. 
I have more test tables, more x's and y's than in the toy example below. 
Thanks in advance for your help.

For example :
test1 <- data.frame(rbind(c(0.1,0.2),0.3,0.1))
rownames(test1)=c('y1','y2','y3')
colnames(test1) = c('x1','x2');
test2 <- data.frame(rbind(c(0.8,0.9,0.5),c(0.5,0.1,0.6)))
rownames(test2) = c('y2','y5')
colnames(test2) = c('x1','x3','x2')

test1
       x1   x2
y1  0.1  0.2
y2  0.3  0.3
y3  0.1  0.1

test2
       x1   x3   x2
y2  0.8  0.9  0.5
y5  0.5  0.1  0.6

I would like to combine test1 and test2 such that if the column name and row name are both the same they are combined.

combined_test
           x1              x2             x3
y1      0.1              0.2           NA
y2  (0.3,0.8)    (0.3,0.5)      0.9
y3      0.1              0.1           NA
y5      0.5              0.6           0.1