@CanIgnoreReturnValue
    PatternAsserter doesNotMatch(String... paths) {
      for (String path : paths) {
        assertFalse(
            "glob '" + matcher + "' should not have matched '" + path + "'",
            matcher.matches(fake(path)));
        if (realMatcher != null) {
          Path realPath = Paths.get(path);
          assertFalse(
              "real matcher '" + realMatcher + "' matched '" + realPath + "'",
              realMatcher.matches(realPath));
        }
      }
      return this;
    }
Override to return a real matcher for the given pattern.
jimfs/src/test/java/com/google/common/jimfs/AbstractPathMatcherTest.java