A CallMatcher is a special matcher used to match method calls (i.e. a method name and set of arguments). It is not a Matcher like the unit test Matcher, but instead represents a method name and a collection of Matchers, one per argument, that will be applied to the parameters to decide if the method call is a match.

class CallMatcher {
  Matcher nameFilter;
  List<Matcher> argMatchers;

  /**
   * Constructor for [CallMatcher]. [name] can be null to
   * match anything, or a literal [String], a predicate [Function],
   * or a [Matcher]. The various arguments can be scalar values or
   * [Matcher]s.
   */
  CallMatcher([name,
              arg0 = _noArg,
              arg1 = _noArg,
              arg2 = _noArg,
              arg3 = _noArg,
              arg4 = _noArg,
              arg5 = _noArg,
              arg6 = _noArg,
              arg7 = _noArg,
              arg8 = _noArg,
              arg9 = _noArg]) {
    if (name == null) {
      nameFilter = anything;
    } else {
      nameFilter = wrapMatcher(name);
    }
    argMatchers = new List<Matcher>();
    if (arg0 === _noArg) return;
    argMatchers.add(wrapMatcher(arg0));
    if (arg1 === _noArg) return;
    argMatchers.add(wrapMatcher(arg1));
    if (arg2 === _noArg) return;
    argMatchers.add(wrapMatcher(arg2));
    if (arg3 === _noArg) return;
    argMatchers.add(wrapMatcher(arg3));
    if (arg4 === _noArg) return;
    argMatchers.add(wrapMatcher(arg4));
    if (arg5 === _noArg) return;
    argMatchers.add(wrapMatcher(arg5));
    if (arg6 === _noArg) return;
    argMatchers.add(wrapMatcher(arg6));
    if (arg7 === _noArg) return;
    argMatchers.add(wrapMatcher(arg7));
    if (arg8 === _noArg) return;
    argMatchers.add(wrapMatcher(arg8));
    if (arg9 === _noArg) return;
    argMatchers.add(wrapMatcher(arg9));
  }

  /**
   * We keep our behavior specifications in a Map, which is keyed
   * by the [CallMatcher]. To make the keys unique and to get a
   * descriptive value for the [CallMatcher] we have this override
   * of [toString()].
   */
  String toString() {
    Description d = new StringDescription();
    d.addDescriptionOf(nameFilter);
    // If the nameFilter was a simple string - i.e. just a method name -
    // strip the quotes to make this more natural in appearance.
    if (d.toString()[0] == "'") {
      d.replace(d.toString().substring(1, d.toString().length - 1));
    }
    d.add('(');
    for (var i = 0; i < argMatchers.length; i++) {
      if (i > 0) d.add(', ');
      d.addDescriptionOf(argMatchers[i]);
    }
    d.add(')');
    return d.toString();
  }

  /**
   * Given a [method] name and list of [arguments], return true
   * if it matches this [CallMatcher.
   */
  bool matches(String method, List arguments) {
    var matchState = new MatchState();
    if (!nameFilter.matches(method, matchState)) {
      return false;
    }
    var numArgs = (arguments == null) ? 0 : arguments.length;
    if (numArgs < argMatchers.length) {
      throw new Exception("Less arguments than matchers for $method.");
    }
    for (var i = 0; i < argMatchers.length; i++) {
      if (!argMatchers[i].matches(arguments[i], matchState)) {
        return false;
      }
    }
    return true;
  }
}