Changed the syntax some. All the handling of variable argument lists is

lib/unittest/mock.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * The error formatter for mocking is a bit different from the default one
  * for unit testing; instead of the third argument being a 'reason'
  * it is instead a [signature] describing the method signature filter
  * that was used to select the logs that were verified.
  */
@@ skipping 22 matching lines @@
   }
 }
 
 _MockFailureHandler _mockFailureHandler = null;
 
 /**
  * [_noArg] is a sentinel value representing no argument.
  */
 final _noArg = const _Sentinel();
 
+/** The ways in which a call to a mock method can be handled. */
+final RETURN = 0;
+final THROW = 1;
+final PROXY = 2;
+
 /**
  * The behavior of a method call in the mock library is specified
  * with [BehaviorValue]s. A [BehaviorValue] has a [value] to throw
  * or return (depending on whether [isThrow] is true or not, respectively),
  * and can either be one-shot, multi-shot, or infinitely repeating,
  * depending on the value of [count (1, greater than 1, or 0 respectively).
  */
 class BehaviorValue {
   var value;
-  bool isThrow;
+  int action;
   int count;
-  BehaviorValue(this.value, [this.count = 1, this.isThrow = false]);
+  BehaviorValue(this.value, [this.count = 1, this.action = RETURN]);
 }
 
 /**
  * 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 collection of [Matcher]s,
  * one per argument, that will be applied to the parameters to decide if
  * the method call is a match.
  */
 class CallMatcher {
@@ skipping 50 matching lines @@
     }
     d.add(')');
     return d.toString();
   }
 
   /**
    * Given a [method] name oand list of [arguments], return true
    * if it matches this [CallMatcher.
    */
   bool matches(String method, List arguments) {
-    if (method != this.name || arguments.length != argMatchers.length) {
+    if (method != this.name) {
       return false;
     }
-    for (var i = 0; i < arguments.length; i++) {
+    if (arguments.length < argMatchers.length) {
+      throw new Exception("Less arguments than matchers for $name");
+    }
+    for (var i = 0; i < argMatchers.length; i++) {
       if (!argMatchers[i].matches(arguments[i])) {
         return false;
       }
     }
     return true;
   }
 }
 
+/** [callstTo] returns a CallMatcher for the specified signature. */
+CallMatcher callsTo(String method, [ arg0 = _noArg,
+                        arg1 = _noArg,
+                        arg2 = _noArg,
+                        arg3 = _noArg,
+                        arg4 = _noArg,
+                        arg5 = _noArg,
+                        arg6 = _noArg,
+                        arg7 = _noArg,
+                        arg8 = _noArg,
+                        arg9 = _noArg]) {
+  return new CallMatcher(method, arg0, arg1, arg2, arg3, arg4,
+      arg5, arg6, arg7, arg8, arg9);
+}
+
 /**
  * A [Behavior] represents how a [Mock] will respond to one particular
  * type of method call.
  */
 class Behavior {
   CallMatcher matcher; // The method call matcher.
-  List<BehaviorValue> returnValues; // The values to return/throw.
+  List<BehaviorValue> actions; // The values to return/throw or proxies to call.
 
   Behavior (this.matcher) {
-    returnValues = new List<BehaviorValue>();
+    actions = new List<BehaviorValue>();
   }
 
   /**
    * [thenReturn] creates a return value, that is returned [count]
    * times (1 by default).
    */
   Behavior thenReturn(value, [count = 1]) {
-    returnValues.add(new BehaviorValue(value, count));
+    actions.add(new BehaviorValue(value, count, RETURN));
     return this; // For chaining calls.
   }
 
   /** [alwaysReturn] creates a repeating return value. */
   Behavior alwaysReturn(value) {
     return thenReturn(value, 0);
   }
 
   /**
    * [thenThrow] creates an exception, that is thrown [count]
    * times (1 by default).
    */
   Behavior thenThrow(value, [count = 1]) {
-    returnValues.add(new BehaviorValue(value, count, true));
+    actions.add(new BehaviorValue(value, count, THROW));
     return this; // For chaining calls.
   }
 
   /** [alwaysThrow] creates a repeating exception. */
   Behavior alwaysThrow(value) {
     return thenThrow(value, 0);
   }
 
+  /**
+   * [thenCall] creates a proxy, that is called [count]
+   * times (1 by default).
+   */
+  Behavior thenCall(value, [count = 1]) {
+    actions.add(new BehaviorValue(value, count, PROXY));
+    return this; // For chaining calls.
+  }
+
+  /** [alwaysCall] creates a repeating proxy call. */
+  Behavior alwaysCall(value) {
+    return thenCall(value, 0);
+  }
+
   /** [matches] return true if a method call matches the [Behavior]. */
   bool matches(name, args) => matcher.matches(name, args);
 }
 
 /**
  * Every call to a [Mock] object method is logged. The logs are
  * kept in instances of [LogEntry].
  */
 class LogEntry {
   final String name; // The method name.
   final List args; // The parameters.
-  final BehaviorValue result; // The behavior that resulted.
+  final int action; // The behavior that resulted.
+  final value; // The value that was returned (if no throw).
 
-  const LogEntry(this.name, this.args, this.result);
+  const LogEntry(this.name, this.args, this.action, [this.value = null]);
 }
 
 /**
  * We do verification on a list of [LogEntry]s. To allow chaining
  * of calls to verify, we encapsulate such a list in the [LogEntryList]
  * class.
  */
 class LogEntryList {
   final String filter;
   final List<LogEntry> logs;
   const LogEntryList(this.logs, [this.filter = null]);
 
   /** Add a [LogEntry] to the log. */
   add(LogEntry entry) => logs.add(entry);
 
   /**
    * Create a new [LogEntryList] consisting of [LogEntry]s from
-   * this list that match the specified [logfilter].
+   * this list that match the specified [logfilter]. If [destructive]
+   * is true, the log entries are removed from the original list.
    */
-  LogEntryList getMatches(CallMatcher logfilter) {
+  LogEntryList getMatches(CallMatcher logfilter, bool destructive) {
     LogEntryList rtn =
         new LogEntryList(new List<LogEntry>(), logfilter.toString());
     for (var i = 0; i < logs.length; i++) {
       LogEntry entry = logs[i];
       if (logfilter.matches(entry.name, entry.args)) {
         rtn.add(entry);
+        if (destructive) {
+          logs.removeRange(i--, 1);
+        }
       }
     }
     return rtn;
   }
 
   /** Apply a unit test [Matcher] to the [LogEntryList]. */
   LogEntryList verify(Matcher matcher) {
     if (_mockFailureHandler == null) {
       _mockFailureHandler =
           new _MockFailureHandler(getOrCreateExpectFailureHandler());
@@ skipping 49 matching lines @@
 /** [calledOnce] matches exactly one call. */
 final Matcher calledOnce = const _TimesMatcher(1, 1);
 
 /** [calledAtLeastOnce] matches one or more calls. */
 final Matcher calledAtLeastOnce = const _TimesMatcher(1);
 
 /** [calledAtMostOnce] matches zero or one call. */
 final Matcher calledAtMostOnce = const _TimesMatcher(0, 1);
 
 /**
+ * [_ResultMatcher]s are used to make assertions about the results
+ * of method calls.
+ */
+class _ResultMatcher extends BaseMatcher {
+  final int action;
+  final value;
+  final int count; // -1 for all, 0 for none, 1 for some.
+
+  const _ResultMatcher(this.action, this.value, this.count);
+
+  bool matches(log) {
+    for (LogEntry entry in log) {
+      // normalize the action; PROXY is like RETURN.
+      int eaction = (entry.action == THROW) ? THROW : RETURN;
+      if (eaction == action && value.matches(entry.value)) {
+        if (count == 0) {
+          return false;
+        } else if (count == 1) {
+          return true;
+        }
+      } else {
+        // Mismatch.
+        if (count == -1) { // We need just one mismatch to fail.
+          return false;
+        }
+      }
+    }
+    // If we get here, then if count is -1 we got all matches and
+    // this is success; otherwise we got all mismatched which is
+    // success for count == 0 and failure for count == 1.
+    return (count != 1);
+  }
+  Description describe(Description description) {
+    description.add(' to ');
+    description.add(count == -1 ? 'alway ' :
+        (count == 0 ? 'never ' : 'sometimes '));
+    if (action == RETURN || action == PROXY)
+      description.add('return ');
+    else
+      description.add('throw ');
+    return description.addDescriptionOf(value);
+  }
+  Description describeMismatch(log, Description mismatchDescription) {
+    if (count != 1) {
+      mismatchDescription.add(entry.value);
+      for (LogEntry entry in log) {
+        if (entry.action != action || !value.matches(entry.value)) {
+          if (entry.action == RETURN || entry.action == PROXY)
+            mismatchDescription.add('returned ');
+          else
+            mismatchDescription.add('threw ');
+          mismatchDescription.add(entry.value);
+          mismatchDescription.add(' at least once');
+          break;
+        }
+      }
+    } else {
+      mismatchDescription.add('never did');
+    }
+    return mismatchDescription;
+  }
+}
+
+/**
+ *[alwaysReturned] asserts that all matching calls to a method returned
+ * a value that matched [value].
+ */
+Matcher alwaysReturned(value) =>
+    new _ResultMatcher(RETURN, wrapMatcher(value), -1);
+
+/**
+ *[sometimeReturned] asserts that at least one matching call to a method
+ * returned a value that matched [value].
+ */
+Matcher sometimeReturned(value) =>
+    new _ResultMatcher(RETURN, wrapMatcher(value), 1);
+
+/**
+ *[neverReturned] asserts that no matching calls to a method returned
+ * a value that matched [value].
+ */
+Matcher neverReturned(value) =>
+    new _ResultMatcher(RETURN, wrapMatcher(value), 0);
+
+/**
+ *[alwaysThrew] asserts that all matching calls to a method threw
+ * a value that matched [value].
+ */
+Matcher alwaysThrew(value) =>
+    new _ResultMatcher(THROW, wrapMatcher(value), -1);
+
+/**
+ *[sometimeThrew] asserts that at least one matching call to a method threw
+ * a value that matched [value].
+ */
+Matcher sometimeThrew(value) =>
+  new _ResultMatcher(THROW, wrapMatcher(value), 1);
+
+/**
+ *[neverThrew] asserts that no matching call to a method threw
+ * a value that matched [value].
+ */
+Matcher neverThrew(value) =>
+  new _ResultMatcher(THROW, wrapMatcher(value), 0);
+
+/**
  * [Mock] is the base class for all mocked objects, with
  * support for basic mocking.
  *
  * To create a mock objects for some class T, create a new class using:
  *
  *     class MockT extends Mock implements T {};
  *
  * Then specify the behavior of the Mock for different methods using
- * [when] (to select the method and parameters) and [thenReturn],
- * [alwaysReturn], [thenThrow] and/or [alwaysThrow].
+ * [whenThereAre] (to select the method and parameters) and [thenReturn],
+ * [alwaysReturn], [thenThrow], [alwaysThrow], [thenCall] or [alwaysCall].
+ * [thenReturn], [thenThrow] and [thenCall] are one-shot so you would
+ * typically call these more than once to specify a sequence of actions;
+ * this can be done with chained calls, e.g.:
+ *
+ *      m.whenThereAre(callsTo('foo')).
+ *          thenReturn(0).thenReturn(1).thenReturn(2);
+ *
+ * [thenCall] and [alwaysCall] allow you to proxy mocked methods, chaining
+ * to some other implementation. This provides a way to implement 'spies'.
  *
  * You can then use the mock object. Once you are done, to verify the
- * behavior, use [verify] to extract a relevant subset of method call
- * logs and apply [Matchers] to these.
+ * behavior, use [forThe] to extract a relevant subset of method call
+ * logs and apply [Matchers] to these through calling [verify].
  *
  * Limitations:
  * - only positional parameters are supported (up to 10);
  * - to mock getters you will need to include parentheses.
  *
  * Here is a simple example:
  *
  *     class MockList extends Mock implements List {};
  *
  *     List m = new MockList();
- *     m.when('add', anything).alwaysReturn(0);
+ *     m.whenThereAre(callsTo('add', anything)).alwaysReturn(0);
  *
  *     m.add('foo');
  *     m.add('bar');
  *
- *     m.verify('add', anything, was:calledExactly(2));
- *     m.verify('add', 'foo', was:calledOnce);
- *     m.verify('add', 'isNull, was:neverCalled);
+ *     m.forThe(callsTo('add', anything)).verify(calledExactly(2));
+ *     m.forThe(callsTo('add', 'foo')).verify(calledOnce);
+ *     m.forThe(callsTo('add', 'isNull)).verify(neverCalled);
+ *
+ * Note that we don't need to provide argument matchers for all arguments,
+ * but we do need to provide arguments for all matchers. So this is allowed:
+ *
+ *     m.whenThereAre(callsTo('add')).alwaysReturn(0);
+ *     m.add(1, 2);
+ *
+ * But this is not allowed and will throw an exception:
+ *
+ *     m.whenThereAre(callsTo('add', anything, anything)).alwaysReturn(0);
+ *     m.add(1);
+ *
+ * Here is a way to implement a 'spy':
+ *
+ *     class Foo {
+ *       bar(a, b, c) => a + b + c;
+ *     }
+ *
+ *     class MockFoo extends Mock implements Foo {
+ *       Foo real;
+ *       MockFoo() {
+ *         real = new Foo();
+ *         this.whenThereAre(callsTo('bar')).alwaysCall(real.bar);
+ *       }
+ *     }
+ *
  */
 class Mock {
   Map<String,Behavior> behaviors; /** The set of [behavior]s supported. */
   LogEntryList log; /** The [log] of calls made. */
 
   Mock() {
     behaviors = new Map<String,Behavior>();
     log = new LogEntryList(new List<LogEntry>());
   }
 
   /**
-   * [when] is used to create a new or extend an existing [Behavior].
-   * The [method] name and the argument [Matcher] is specified. A
-   * corresponding [CallMatcher] is created, and the [Behavior]s for
-   * its signature are returned (being created first if needed).
+   * [whenThereAre] is used to create a new or extend an existing [Behavior].
+   * A [CallMatcher] [filter] must be supplied, and the [Behavior]s for
+   * that signature are returned (being created first if needed).
+   *
+   * The name [whenThereAre] was chosen to flow grammatically with the
+   * typical use case:
+   *
+   *     mock.whenThereAre(callsTo(...)).thenAlwaysReturn(...);
    */
-  Behavior when(String method, [
-       arg0 = _noArg,
-       arg1 = _noArg,
-       arg2 = _noArg,
-       arg3 = _noArg,
-       arg4 = _noArg,
-       arg5 = _noArg,
-       arg6 = _noArg,
-       arg7 = _noArg,
-       arg8 = _noArg,
-       arg9 = _noArg]) {
-    CallMatcher logfilter = new CallMatcher(method,
-        arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9);
-    String key = logfilter.toString();
+  Behavior whenThereAre(CallMatcher filter) {
+    String key = filter.toString();
     if (!behaviors.containsKey(key)) {
-      Behavior b = new Behavior(logfilter);
+      Behavior b = new Behavior(filter);
       behaviors[key] = b;
       return b;
     } else {
       return behaviors[key];
     }
   }
 
   /**
    * This is the handler for method calls. We loo through the list
    * of [Behavior]s, and find the first match that still has return
    * values available, and then do the action specified by that
    * return value. If we find no [Behavior] to apply an exception is
    * thrown.
    */
   noSuchMethod(String name, List args) {
     for (String k in behaviors.getKeys()) {
       Behavior b = behaviors[k];
       if (b.matches(name, args)) {
-        List rv = b.returnValues;
-        if (rv == null || rv.length == 0) {
+        List actions = b.actions;
+        if (actions == null || actions.length == 0) {
           continue; // No return values left in this Behavior.
         }
         // Get the first response.
-        BehaviorValue bv = rv[0];
+        BehaviorValue bv = actions[0];
         // If it is exhausted, remove it from the list.
         // Note that for endlessly repeating values, we started the count at
         // 0, so we get a potentially useful value here, which is the
         // (negation of) the number of times we returned the value.
         if (--bv.count == 0) {
-          rv.removeRange(0, 1);
-          if (rv.length == 0) {
+          actions.removeRange(0, 1);
+          if (actions.length == 0) {
             // Remove the behavior. Note that in the future there
             // may be some value in preserving the behaviors for
             // auditing purposes (e.g. how many times was this behavior used?).
             // If we do decide to keep them and perf is an issue instead of
             // deleting we could move this to a separate list.
             behaviors.remove(k);
           }
         }
-        // Log the method call and the response.
-        log.add(new LogEntry(name, args, bv));
         // Do the response.
-        if (bv.isThrow) {
-          throw bv.value;
-        } else {
-          return bv.value;
+        switch (bv.action) {
+          case RETURN:
+            log.add(new LogEntry(name, args, bv.action, bv.value));
+            return bv.value;
+          case THROW:
+            log.add(new LogEntry(name, args, bv.action, bv.value));
+            throw bv.value;
+          case PROXY:
+            var rtn;
+            switch (args.length) {
+              case 0:
+                rtn = bv.value();
+                break;
+              case 1:
+                rtn = bv.value(args[0]);
+                break;
+              case 2:
+                rtn = bv.value(args[0], args[1]);
+                break;
+              case 3:
+                rtn = bv.value(args[0], args[1], args[2]);
+                break;
+              case 4:
+                rtn = bv.value(args[0], args[1], args[2], args[3]);
+                break;
+              case 5:
+                rtn = bv.value(args[0], args[1], args[2], args[3], args[4]);
+                break;
+              case 6:
+                rtn = bv.value(args[0], args[1], args[2], args[3],
+                    args[4], args[5]);
+                break;
+              case 7:
+                rtn = bv.value(args[0], args[1], args[2], args[3],
+                    args[4], args[5], args[6]);
+                break;
+              case 8:
+                rtn = bv.value(args[0], args[1], args[2], args[3],
+                    args[4], args[5], args[6], args[7]);
+                break;
+              case 9:
+                rtn = bv.value(args[0], args[1], args[2], args[3],
+                    args[4], args[5], args[6], args[7], args[8]);
+                break;
+              case 9:
+                rtn = bv.value(args[0], args[1], args[2], args[3],
+                    args[4], args[5], args[6], args[7], args[8], args[9]);
+                break;
+              default:
+                throw new Exception(
+                    "Cannot proxy calls with more than 10 parameters");
+            }
+            log.add(new LogEntry(name, args, bv.action, rtn));
+            return rtn;
         }
       }
     }
     throw new Exception('No behavior specified for method $name');
   }
 
   /**
-   * [verify] extracts all calls from the object log that match the
-   * method signature, then applies the [was] matcher. The matching
-   * list of [LogEntry]s is returned so that further calls to verify()
-   * can be chained .
+   * [forThe] extracts all calls from the object log that match the
+   * [logFilter] [CallMatcher], and returns the matching list of
+   * [LogEntry]s. If [destructive] is false (the default) the matching
+   * calls are left in the mock object's log, else they are removed.
+   * Removal allows us to verify a set of interactions and then verify
+   * that there are no other interactions left.
+   *
+   * The name [forThe] was chosen to flow grammatically with [callsTo],
+   * as this is usually used in the form:
+   *
+   *     mock.forThe(callsTo(...)).verify(...);

[Siggi Cherem (dart-lang), 2012/06/28 17:51:43]

should we keep this example below? 

getLogs(mock, callsTo(...)).verify(...);

    */
-  LogEntryList verify(String method, [ arg0 = _noArg,
-                          arg1 = _noArg,
-                          arg2 = _noArg,
-                          arg3 = _noArg,
-                          arg4 = _noArg,
-                          arg5 = _noArg,
-                          arg6 = _noArg,
-                          arg7 = _noArg,
-                          arg8 = _noArg,
-                          arg9 = _noArg,
-                          Matcher was = calledOnce]) {
-    CallMatcher logfilter = new CallMatcher(method,
-      arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9);
-    LogEntryList _logs = log.getMatches(logfilter);
-    _logs.verify(was);
-    return _logs;
+  LogEntryList forThe(CallMatcher logFilter, [bool destructive = false]) {
+    return log.getMatches(logFilter, destructive);
   }
 
   /** [verifyZeroInteractions] returns true if no calls were made */
   bool verifyZeroInteractions() => log.logs.length == 0;
-
 }
 
+