Is there a way to generate unit test to test my gr

I created my grammar using antlr4 but I want to test robustess
is there an automatic tool or a good way to do that fast

Thanks :)

回答1:

The only way I found to create unit tests for a grammar is to create a number of examples from a written spec of the given language. This is neither fast, nor complete, but I see no other way.

You could be tempted to create test cases directly from the grammar (writing a tool for that isn't that hard). But think a moment about this. What would you test then? Your unit tests would always succeed, unless you use generated test cases from an earlier version of the grammar.

A special case is when you write a grammar for a language that has already a grammar for another parser generation tool. In that case you could use the original grammar to generate test cases which you then can use to test your new grammar for conformity.

However, I don't know any tool that can generate the test cases for you.

Update

Meanwhile I got another idea that would allow for better testing: have a sentence generator that generates random sentences from your grammar (I'm currently working on one in my Visual Studio Code ANTLR4 extension). The produced sentences can then be examined using a heuristic approach, for their validity:

Confirm the base structure.
Check for mandatory keywords and their correct order.
Check that identifiers and strings are valid.
Watch out for unusual constructs that are not valid according to language.
...

This would already cover a good part of the language, but has limits. Matching code and generating it are not 1:1 operations. A grammar rule that matches certain (valid) input might generate much more than that (and can so produce invalid input).

回答2:

As it's so hard to find real unit tests for ANTLR, I wrote 2 articles about it:

Unit test for Lexer
Unit test for Parser

A Lexer test checks whether a given text is read and converted to the expected Token sequences. It's useful for instance to avoid ambiguity errors.

A Parser test take a sequence of tokens (that is, it starts after the lesser part) and checks whether that token sequence traverses the expected rules ( java methods).