test case

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A lawsuit brought in part for the purpose of obtaining a judicial decision on an unclear point of law, especially involving the constitutionality of a statute.
• noun An action that establishes a precedent for such a lawsuit.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun law A legal action intended to set a precedent.
• noun computing Any of a set of conditions and variables used to test an application.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a representative legal action whose outcome is likely to become a precedent