Question about debugging jobs and transformation

I have a question about debug a job.

I have a job with 3 transformations. The dataset results of each transformation have to be passed to the next transformation.
I used the step "copy rows to result" and "get rows from result" to connect the flow datasets between transformations.

In order to test each transformations one by one, I use temporary files:
tran1 -> make steps...write file1
tran2 -> read file1 make steps write file2 ( I test it individually)
tran3 -> read file2 make steps... ( I test it individually)

Once tested each transformation I create the job and replace temporary files for ""copy/get rows to result"

My problem now is if testing my job I have an error in a tranformtion...how I test now this transformation individualy??,
do I have to go back to the "temporary files"

I would like to know the optimal way to test job and transformations.

Any help, will be greatly appreciated,

Thanks