Software test scripts are conventionally composed ad hoc by a coder. Some software development tools help automate testing by recording tests that are run allowing playback of the test routines. However an entire test routine is rarely if ever applicable to more than one release of one application.
Data-driven testing adds some modularity by keeping test input and output values separate from the test procedure but the procedure itself is still in a monolithic script.
Keyword-driven testing breaks the test procedure into logical components that can then be used repeatedly in the assembly of new test scripts.