Some more changes that came out of writing an article on mocks.

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 23 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;
+final IGNORE = 0;

[Jennifer Messerly, 2012/06/29 23:24:09]

might want to wrap these in the enum pattern

+final RETURN = 1;

[Jennifer Messerly, 2012/06/29 23:24:09]

also the ones after the first one could use doc comments

+final THROW = 2;
+final PROXY = 3;
 
 /**
  * The behavior of a method call in the mock library is specified
  * with [Responder]s. A [Responder] 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 Responder {
   var value;
   int action;
   int count;
   Responder(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.
+ * unit test [Matcher], but instead represents a method name and 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 {
   String name;
   List<Matcher> argMatchers;
 
   CallMatcher(String method, [
               arg0 = _noArg,
               arg1 = _noArg,
               arg2 = _noArg,
               arg3 = _noArg,
@@ skipping 145 matching lines @@
     return thenCall(value, 0);
   }
 
   /** Returns true if a method call matches the [Behavior]. */
   bool matches(name, args) => matcher.matches(name, args);
 
   /** Returns the [matcher]'s representation. */
   String toString() => matcher.toString();
 }
 
+String pad2(int v) {
+  String s = '0$v';
+  return s.substring(s.length-2);
+}
+
 /**
  * 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.
+  Date when; // The time of the event.

[Jennifer Messerly, 2012/06/29 23:24:09]

can this be final, and set it in an initializer:

LogEntry(this.mockName, ...) {
    : when = new Date.now();

+  final String mockName; // The mock object name, if any.
+  final String methodName; // The method name.
   final List args; // The parameters.
   final int action; // The behavior that resulted.
   final value; // The value that was returned (if no throw).
 
-  const LogEntry(this.name, this.args, this.action, [this.value = null]);
+  LogEntry(this.mockName, this.methodName,
+      this.args, this.action, [this.value = null]) {

[Jennifer Messerly, 2012/06/29 23:24:09]

nit: can write this as "[this.value]". The "= null" is implied now

+    when = new Date.now();
+  }
+
+  String toString([Date baseTime = null]) {
+    Description d = new StringDescription();
+    if (baseTime == null) {
+      // Show absolute time.
+      d.add('${when.hour}:${pad2(when.minute)}:'
+          '${pad2(when.second)}.${when.millisecond}>  ');
+    } else {
+      // Show relative time.
+      int delta = when.millisecondsSinceEpoch - baseTime.millisecondsSinceEpoch;
+      int secs = (delta / 1000).toInt();

[Jennifer Messerly, 2012/06/29 23:24:09]

nit: delta ~/ 1000
also, shouldn't need .toInt, if you do that's a bug.

+      int msecs = (delta % 1000).toInt();

[Jennifer Messerly, 2012/06/29 23:24:09]

likewise, this shouldn't need .toInt

+      d.add('$secs.$msecs>  ');
+    }
+    d.add('${_qualifiedName(mockName, methodName)}(');
+    for (var i = 0; i < args.length; i++) {
+      if (i != 0) d.add(', ');
+      d.addDescriptionOf(args[i]);
+    }
+    d.add(') ${action == THROW ? "threw" : "returned"} ');
+    d.addDescriptionOf(value);
+    return d.toString();
+  }
 }
 
+/** Utility function for optionally qualified method names */

[Jennifer Messerly, 2012/06/29 23:24:09]

nit: extra newline here

+
+String _qualifiedName(String owner, String method) {
+  if (owner == null) {
+    return method;
+  } else {
+    return '$owner.$method';
+  }
+}
 /**
  * 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]);
+  List<LogEntry> logs;
+
+  LogEntryList([this.filter = null]) {
+    logs = new List<LogEntry>();
+  }
 
   /** 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]. If [destructive]
+   * this list that match the specified [mockName] and [logfilter].
+   * If [mockName] is null, all entries will be checked. If [destructive]
    * is true, the log entries are removed from the original list.
    */
-  LogEntryList getMatches(CallMatcher logfilter, bool destructive) {
-    LogEntryList rtn =
-        new LogEntryList(new List<LogEntry>(), logfilter.toString());
+  LogEntryList getMatches(String mockName,
+                          CallMatcher logFilter,
+                          [Matcher actionMatcher = null,
+                          bool destructive = false]) {
+    String filterName = _qualifiedName(mockName, logFilter.toString());
+    LogEntryList rtn = new LogEntryList(filterName);
     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);
+      if (mockName != null && mockName != entry.mockName) {
+        continue;
+      }
+      if (logFilter.matches(entry.methodName, entry.args)) {
+        if (actionMatcher == null || actionMatcher.matches(entry)) {
+          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());
     }
     expect(logs, matcher, filter, _mockFailureHandler);
     return this;
   }
+
+  String toString([Date baseTime = null]) {
+    String s = '';
+    for (var e in logs) {
+      s = '$s${e.toString(baseTime)}\n';
+    }
+    return s;
+  }
 }
 
 /**
  * [_TimesMatcher]s are used to make assertions about the number of
  * times a method was called.
  */
 class _TimesMatcher extends BaseMatcher {
   final int min, max;
 
   const _TimesMatcher(this.min, [this.max = -1]);
@@ skipping 11 matching lines @@
     } else {
       description.add('between $min and $max');
     }
     return description.add(' times');
   }
 
   Description describeMismatch(log, Description mismatchDescription) =>
       mismatchDescription.add('was called ${log.length} times');
 }
 
-/** [calledExactly] matches an exact number of calls. */
-Matcher calledExactly(count) {
+/** [happenedExactly] matches an exact number of calls. */

[Jennifer Messerly, 2012/06/29 23:24:09]

not sure you really need the link, since it's just linking to itself.

However, commenting on and linking to the other happened* matchers in prose
would be neat. (It might almost be worth making _TimesMatcher public, so you
have a class to put that commentary ... )

+Matcher happenedExactly(count) {
   return new _TimesMatcher(count, count);
 }
 
-/** [calledAtLeast] matches a minimum number of calls. */
-Matcher calledAtLeast(count) {
+/** [happenedAtLeast] matches a minimum number of calls. */
+Matcher happenedAtLeast(count) {
   return new _TimesMatcher(count);
 }
 
-/** [calledAtMost] matches a maximum number of calls. */
-Matcher calledAtMost(count) {
+/** [happenedAtMost] matches a maximum number of calls. */
+Matcher happenedAtMost(count) {
   return new _TimesMatcher(0, count);
 }
 
-/** [neverCalled] matches zero calls. */
-final Matcher neverCalled = const _TimesMatcher(0, 0);
+/** [neverHappened] matches zero calls. */
+final Matcher neverHappened = const _TimesMatcher(0, 0);
 
-/** [calledOnce] matches exactly one call. */
-final Matcher calledOnce = const _TimesMatcher(1, 1);
+/** [happenedOnce] matches exactly one call. */
+final Matcher happenedOnce = const _TimesMatcher(1, 1);
 
-/** [calledAtLeastOnce] matches one or more calls. */
-final Matcher calledAtLeastOnce = const _TimesMatcher(1);
+/** [happenedAtLeastOnce] matches one or more calls. */
+final Matcher happenedAtLeastOnce = const _TimesMatcher(1);
 
-/** [calledAtMostOnce] matches zero or one call. */
-final Matcher calledAtMostOnce = const _TimesMatcher(0, 1);
+/** [happenedAtMostOnce] matches zero or one call. */
+final Matcher happenedAtMostOnce = const _TimesMatcher(0, 1);
 
-/** Special values for use with [_ResultMatcher] [frequency]. */
-final int ALL = 0;
-final int SOME = 1;
-final int NONE = 2;
 /**
  * [_ResultMatcher]s are used to make assertions about the results
- * of method calls. When filtering an execution log by calling
- * [forThe], a [LogEntrySet] of matching call logs is returned;
- * [_ResultMatcher]s can then assert various things about this
- * (sub)set of logs.
+ * of method calls. These can be used as optional parameters to getLogs().
  */
 class _ResultMatcher extends BaseMatcher {
   final int action;
   final value;
+
+  const _ResultMatcher(this.action, this.value);
+
+  bool matches(item) {
+    if (item is! LogEntry) {
+      return false;
+    }
+    // normalize the action; PROXY is like RETURN.
+    int eaction = (item.action == THROW) ? THROW : RETURN;
+    return (eaction == action && value.matches(item.value));
+  }
+
+  Description describe(Description description) {
+    description.add(' to ');
+    if (action == RETURN || action == PROXY)
+      description.add('return ');
+    else
+      description.add('throw ');
+    return description.addDescriptionOf(value);
+  }
+
+  Description describeMismatch(log, Description mismatchDescription) {
+    if (entry.action == RETURN || entry.action == PROXY) {
+      mismatchDescription.add('returned ');
+    } else {
+      mismatchDescription.add('threw ');
+    }
+    mismatchDescription.add(entry.value);
+    return mismatchDescription;
+  }
+}
+
+/**
+ *[returning] matches log entries where the call to a method returned
+ * a value that matched [value].
+ */
+Matcher returning(value) =>
+    new _ResultMatcher(RETURN, wrapMatcher(value));
+
+/**
+ *[throwing] matches log entrues where the call to a method threw
+ * a value that matched [value].
+ */
+Matcher throwing(value) =>
+    new _ResultMatcher(THROW, wrapMatcher(value));
+
+/** Special values for use with [_ResultSetMatcher] [frequency]. */

[Jennifer Messerly, 2012/06/29 23:24:09]

probably shouldn't link to an internal type.
also, these could use individual doc comments or an enum pattern, so they'll be
grouped properly in our docs.

+final int ALL = 0;
+final int SOME = 1;
+final int NONE = 2;
+
+/**
+ * [_ResultSetMatcher]s are used to make assertions about the results
+ * of method calls. When filtering an execution log by calling
+ * [getLogs], a [LogEntrySet] of matching call logs is returned;
+ * [_ResultSetMatcher]s can then assert various things about this
+ * (sub)set of logs.
+ *
+ * We could make this class use _ResultMatcher but it doesn't buy that
+ * match and adds some perf hit, so there is some duplication here.
+ */
+class _ResultSetMatcher extends BaseMatcher {
+  final int action;
+  final value;
   final int frequency; // -1 for all, 0 for none, 1 for some.
 
-  const _ResultMatcher(this.action, this.value, this.frequency);
+  const _ResultSetMatcher(this.action, this.value, this.frequency);
 
   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 (frequency == NONE) {
           return false;
         } else if (frequency == SOME) {
           return true;
@@ skipping 40 matching lines @@
     }
     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), ALL);
+    new _ResultSetMatcher(RETURN, wrapMatcher(value), ALL);
 
 /**
  *[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), SOME);
+    new _ResultSetMatcher(RETURN, wrapMatcher(value), SOME);
 
 /**
  *[neverReturned] asserts that no matching calls to a method returned
  * a value that matched [value].
  */
 Matcher neverReturned(value) =>
-    new _ResultMatcher(RETURN, wrapMatcher(value), NONE);
+    new _ResultSetMatcher(RETURN, wrapMatcher(value), NONE);
 
 /**
  *[alwaysThrew] asserts that all matching calls to a method threw
  * a value that matched [value].
  */
 Matcher alwaysThrew(value) =>
-    new _ResultMatcher(THROW, wrapMatcher(value), ALL);
+    new _ResultSetMatcher(THROW, wrapMatcher(value), ALL);
 
 /**
  *[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), SOME);
+  new _ResultSetMatcher(THROW, wrapMatcher(value), SOME);
 
 /**
  *[neverThrew] asserts that no matching call to a method threw
  * a value that matched [value].
  */
 Matcher neverThrew(value) =>
-  new _ResultMatcher(THROW, wrapMatcher(value), NONE);
+  new _ResultSetMatcher(THROW, wrapMatcher(value), NONE);
+
+/** The shared log used for named mocks. */
+LogEntryList sharedLog = null;
 
 /**
  * [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], [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.when(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 [forThe] to extract a relevant subset of method call
+ * behavior, use [getLogs] to extract a relevant subset of method call
  * logs and apply [Matchers] to these through calling [verify].
  *
+ * A Mock can be given a name when constructed. In this case instead of
+ * keeping its own log, it uses a shared log. This can be useful to get an
+ * audit trail of interleaved behavior. It is the responsibility of the user
+ * to ensure that mock names, if used, are unique.
+ *
  * Limitations:
  * - only positional parameters are supported (up to 10);
  * - to mock getters you will need to include parentheses in the call
  *       (e.g. m.length() will work but not m.length).
  *
  * Here is a simple example:
  *
  *     class MockList extends Mock implements List {};
  *
  *     List m = new MockList();
  *     m.when(callsTo('add', anything)).alwaysReturn(0);
  *
  *     m.add('foo');
  *     m.add('bar');
  *
- *     getLogs(m, callsTo('add', anything)).verify(calledExactly(2));
- *     getLogs(m, callsTo('add', 'foo')).verify(calledOnce);
- *     getLogs(m, callsTo('add', 'isNull)).verify(neverCalled);
+ *     getLogs(m, callsTo('add', anything)).verify(happenedExactly(2));
+ *     getLogs(m, callsTo('add', 'foo')).verify(happenedOnce);
+ *     getLogs(m, callsTo('add', 'isNull)).verify(neverHappened);
  *
  * 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.when(callsTo('add')).alwaysReturn(0);
  *     m.add(1, 2);
  *
  * But this is not allowed and will throw an exception:
  *
  *     m.when(callsTo('add', anything, anything)).alwaysReturn(0);
@@ skipping 10 matching lines @@
  *     class MockFoo extends Mock implements Foo {
  *       Foo real;
  *       MockFoo() {
  *         real = new Foo();
  *         this.when(callsTo('bar')).alwaysCall(real.bar);
  *       }
  *     }
  *
  */
 class Mock {
+  String name;
   Map<String,Behavior> behaviors; /** The set of [behavior]s supported. */
-  LogEntryList log; /** The [log] of calls made. */
+  LogEntryList log; /** The [log] of calls made. Only used if [name] is null. */
+  bool throwIfNoBehavior; /** If false, swallow unknown method calls. */
 
-  Mock() {
+  Mock([this.name = null, this.throwIfNoBehavior = false, this.log = null]) {
+    if (log == null) {
+      log = new LogEntryList();
+    }
     behaviors = new Map<String,Behavior>();
-    log = new LogEntryList(new List<LogEntry>());
   }
 
   /**
    * [when] 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).
    *
    * Typical use case:
    *
    *     mock.when(callsTo(...)).alwaysReturn(...);
    */
   Behavior when(CallMatcher logFilter) {
     String key = logFilter.toString();
     if (!behaviors.containsKey(key)) {
       Behavior b = new Behavior(logFilter);
       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) {
+  noSuchMethod(String method, List args) {
+    bool matchedMethodName = false;
     for (String k in behaviors.getKeys()) {
       Behavior b = behaviors[k];
-      if (b.matches(name, args)) {
+      if (b.matcher.name == method) {
+        matchedMethodName = true;
+      }
+      if (b.matches(method, args)) {
         List actions = b.actions;
         if (actions == null || actions.length == 0) {
           continue; // No return values left in this Behavior.
         }
         // Get the first response.
         Responder response = 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 (--response.count == 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);
-          }
         }
         // Do the response.
         var action = response.action;
         var value = response.value;
         switch (action) {
           case RETURN:
-            log.add(new LogEntry(name, args, action, value));
+            log.add(new LogEntry(name, method, args, action, value));
             return value;
           case THROW:
-            log.add(new LogEntry(name, args, action, value));
+            log.add(new LogEntry(name, method, args, action, value));
             throw value;
           case PROXY:
             var rtn;
             switch (args.length) {
               case 0:
                 rtn = value();
                 break;
               case 1:
                 rtn = value(args[0]);
                 break;
@@ skipping 26 matching lines @@
                     args[4], args[5], args[6], args[7], args[8]);
                 break;
               case 9:
                 rtn = 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, action, rtn));
+            log.add(new LogEntry(name, method, args, action, rtn));
             return rtn;
         }
       }
     }
-    throw new Exception('No behavior specified for method $name');
+    if (matchedMethodName) {
+      // User did specify behavior for this method, but all the
+      // actions are exhausted. This is considered an error.
+      throw new Exception('No more actions for method '

[Jennifer Messerly, 2012/06/29 23:24:09]

is there a more subtype of Exception we could throw here? (or should we create
one?)

+          '${_qualifiedName(name, method)}');
+    } else if (throwIfNoBehavior) {
+      throw new Exception('No behavior specified for method '
+          '${_qualifiedName(name, method)}');
+    }
+    // User hasn't specified behavior for this method; we don't throw
+    // so we can underspecify.
+    log.add(new LogEntry(name, method, args, IGNORE));
   }
 
   /** [verifyZeroInteractions] returns true if no calls were made */
   bool verifyZeroInteractions() => log.logs.length == 0;
-}
 
-/**
- * [getLogs] extracts all calls from the call log of [mock] 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.
- *
- * Typical usage:
- *
- *     getLogs(mock, callsTo(...)).verify(...);
- */
-LogEntryList getLogs(Mock mock, CallMatcher logFilter,
-                    [bool destructive = false]) {
-    return mock.log.getMatches(logFilter, destructive);
+  /**
+   * [getLogs] extracts all calls from the call 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 log, else they are removed. Removal allows
+   * us to verify a set of interactions and then verify that there are
+   * no other interactions left. [actionMatcher] can be used to further
+   * restrict the returned logs based on the action the mock performed.
+   *
+   * Typical usage:
+   *
+   *     getLogs(callsTo(...)).verify(...);
+   */
+  LogEntryList getLogs(CallMatcher logFilter, [Matcher actionMatcher = null,
+      bool destructive = false]) {
+    return log.getMatches(name, logFilter, actionMatcher, destructive);
+  }
 }
 
 
+
+