### Question:
WildcardMatcher { static char charAt(int i, CharSequence firstPart, CharSequence secondPart, int firstPartLength) { return i < firstPartLength ? firstPart.charAt(i) : secondPart.charAt(i - firstPartLength); }  static WildcardMatcher caseSensitiveMatcher(String matcher); static WildcardMatcher matchAll(); static List<WildcardMatcher> matchAllList(); static WildcardMatcher valueOf(final String wildcardString); static boolean isAnyMatch(List<WildcardMatcher> matchers, @Nullable CharSequence s); static boolean isNoneMatch(List<WildcardMatcher> matchers, @Nullable CharSequence s); @Nullable static WildcardMatcher anyMatch(List<WildcardMatcher> matchers, @Nullable CharSequence s); @Nullable static WildcardMatcher anyMatch(List<WildcardMatcher> matchers, CharSequence firstPart, @Nullable CharSequence secondPart); static int indexOfIgnoreCase(final CharSequence haystack1, final CharSequence haystack2, final String needle, final boolean ignoreCase, final int start, final int end); abstract boolean matches(CharSequence s); abstract boolean matches(CharSequence firstPart, @Nullable CharSequence secondPart); @Override boolean equals(Object obj); abstract String getMatcher(); static final String DOCUMENTATION; }### Answer:
@Test void testCharAt() { assertSoftly(softly -> { softly.assertThat(WildcardMatcher.SimpleWildcardMatcher.charAt(0, "foo", "bar", "foo".length())).isEqualTo('f'); softly.assertThat(WildcardMatcher.SimpleWildcardMatcher.charAt(1, "foo", "bar", "foo".length())).isEqualTo('o'); softly.assertThat(WildcardMatcher.SimpleWildcardMatcher.charAt(2, "foo", "bar", "foo".length())).isEqualTo('o'); softly.assertThat(WildcardMatcher.SimpleWildcardMatcher.charAt(3, "foo", "bar", "foo".length())).isEqualTo('b'); softly.assertThat(WildcardMatcher.SimpleWildcardMatcher.charAt(4, "foo", "bar", "foo".length())).isEqualTo('a'); softly.assertThat(WildcardMatcher.SimpleWildcardMatcher.charAt(5, "foo", "bar", "foo".length())).isEqualTo('r'); }); }