11. The computer system of claim 7 wherein the dictionary includes a false synonym for the one input type that corresponds to the starting phrase.
7. A computer system comprising: one or more processors which process program instructions; a memory device connected to said one or more processors; and program instructions residing in said memory device for generating test cases for a text annotator which searches text documents and analyzes them relative to a defined set of tags by receiving a corpus of text fragments without any annotations and a description of the text annotator, determining types of inputs to the text annotator from the description wherein the types of inputs include at least one phrase selected from the group consisting of a person phrase, a date phrase, and a diagnosis phrase, analyzing language structures in the corpus to identify sentence types and grammar constructs wherein the sentence types include at least one sentence selected from the group consisting of a question, a command, a compound sentence, and a conditional sentence, and the analyzing includes performing a slot grammar parse of the corpus to determine various parse trees of the corpus including a most common parse tree, generating a first test case by performing a grammar tree transformation on a first selected fragment of the corpus based on the sentence types and the grammar constructs wherein the first selected fragment is selected in response to a selection bias towards a sentence type which corresponds to the most common parse tree of the corpus, and generating a second test case by replacing at least one starting phrase in the first test case with a substitute phrase from at least one dictionary associated with one of the types of inputs that corresponds to the starting phrase.