A diagnostic test reader includes an assay interface, a locking mechanism, and a test unit. The assay interface is configured to receive a diagnostic assay. The locking mechanism is configured to lock the diagnostic assay within the assay interface in response to one of the diagnostic assay and the diagnostic test reader being given a first push in a first direction toward the other of the diagnostic assay and the diagnostic test reader. The locking mechanism is also configured to unlock the diagnostic assay within the assay interface in response to the one of the diagnostic assay and the diagnostic test reader being given a second push in the first direction. The test unit is configured to analyze the diagnostic assay.