I remember that this test was done in an airplane that my airline was giving back to the lessor, among others, years ago. However I don't know if the result of such test could render an airplane not airworthy.
If it failed the test, the airworthiness of the aircraft would be suspended until it was fixed or possibly deferred using an engineering authorization(doubtful).
There is a airplane leak down check procedure on the 737NG as part of a single pack operational confidence check. Basically; pressurize to 4.2PSIG turn off packs, start timer at 4.0PSIG, stop timer at 2.5PSIG. If it takes less than 100 seconds maintenance is required. Ideal is between 120-130 seconds.