Regex with a dollar sign and a cap sign seems to be buggy during stub generation. (This ticket contains tests.)

[mikhail-putilov]

Bug report

Spring cloud version: 2.1.0.RELEASE. I added new methods to XegerTest which reproduce minimal failing test cases:

package repackaged.nl.flotsam.xeger;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import org.junit.Test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.assertFalse;

public class XegerTest {

	/**
	 * Add general expectations for developers with different knowledge background about regex 
	 */
	@Test
	public void generalExpectationsAboutPipeAndCompiledFlag() {
		String regexAbc = "|abc";
		assertTrue("".matches(regexAbc));
		assertTrue("abc".matches(regexAbc));

		// note that regex is compiled with a flag of zero. Which means that this is false:
		assertFalse("aabc".matches(regexAbc));
	}

	@Test
	public void shouldGenerateTextCorrectlyWithDollarSignInTheEnd() {
		String regex = ".*$";
		// baseline assumption:
		assertTrue("".matches(regex));
		assertTrue("a".matches(regex));

		Xeger generator = new Xeger(regex);
		for (int i = 0; i < 100; i++) {
			String text = generator.generate();
			assertTrue(text.matches(regex));
		}
	}

	@Test
	public void shouldGenerateTextCorrectlyWithCapSignInTheBegging() {
		String regex = "^b*";
		// baseline assumption:
		assertTrue("".matches(regex));
		assertTrue("b".matches(regex));

		Xeger generator = new Xeger(regex);
		for (int i = 0; i < 100; i++) {
			String text = generator.generate();
			assertTrue(text.matches(regex));
		}
	}

	@Test
	public void shouldGenerateTextCorrectlyWithPipeAndDollarSign() {
		String regex = ".$|bca";
		// baseline assumption:
		assertTrue("b".matches(regex));
		assertTrue("bca".matches(regex));
		assertFalse("".matches(regex));
		assertFalse("bc".matches(regex));

		Xeger generator = new Xeger(regex);
		for (int i = 0; i < 100; i++) {
			String text = generator.generate();
			assertTrue(text.matches(regex));
		}
	}

	@Test
	public void shouldGenerateTextCorrectlyWithPipeAndEmptyExpression() {
		String regex = "|bca";
		// baseline assumption:
		assertTrue("".matches(regex));
		assertTrue("bca".matches(regex));
		assertFalse(" ".matches(regex));

		Xeger generator = new Xeger(regex);
		for (int i = 0; i < 100; i++) {
			String text = generator.generate();
			assertTrue(text.matches(regex));
		}
	}
}

For me, it looks like if a developer doesn't know those details about a regex engine beihind, he or she is doomed to spend a lot of time debugging things. Please, take a closer look at Xeger.

[OlgaMaciaszek]

@mikhail-putilov Thanks for reporting this. We have looked at various regex engines and have not found anything better. However, I guess we should add this info to the documentation. Would you be interested in contributing a short paragraph about the possible expected vs. actual behaviours of the engine to our docs as PR?

[mikhail-putilov]

Sure, will do on an upcoming weekend

[mikhail-putilov]

@OlgaMaciaszek done
I'm open to change if something is wrong from my side :-)