More work on the stateful checker; still not perfect, but it's getting better

13 files changed, 281 insertions, 171 deletions

diff --git a/src/main/java/au/id/zancanaro/javacheck/statem/Command.java b/src/main/java/au/id/zancanaro/javacheck/state/Command.java
index a741f0a..afa3957 100644
--- a/src/main/java/au/id/zancanaro/javacheck/statem/Command.java
+++ b/src/main/java/au/id/zancanaro/javacheck/state/Command.java
@@ -1,4 +1,4 @@
-package au.id.zancanaro.javacheck.statem;
+package au.id.zancanaro.javacheck.state;
 
 import au.id.zancanaro.javacheck.Generator;
 
diff --git a/src/main/java/au/id/zancanaro/javacheck/statem/CommandList.java b/src/main/java/au/id/zancanaro/javacheck/state/CommandList.java
index 9e8948a..0426fd3 100644
--- a/src/main/java/au/id/zancanaro/javacheck/statem/CommandList.java
+++ b/src/main/java/au/id/zancanaro/javacheck/state/CommandList.java
@@ -1,9 +1,6 @@
-package au.id.zancanaro.javacheck.statem;
+package au.id.zancanaro.javacheck.state;
 
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 public class CommandList<State> {
     private final List<GeneratedCommand<State, ?, ?>> commands;
@@ -35,11 +32,14 @@ public class CommandList<State> {
             if (!command.preCondition(state, args)) {
                 return CommandResult.fail(state, new Error("Precondition failed"));
             }
-            Result result = command.runCommand(args);
+            Result result = CommandValue.withValues(values, () ->
+                    command.runCommand(args));
             values.put(id, result);
-            State oldState = state;
-            state = command.nextState(state, args, new CommandValue.ConcreteValue<>(id, values));
-            if (!command.postCondition(oldState, state, args, result)) {
+            final State oldState = state;
+            final State newState = CommandValue.withValues(values, () ->
+                    command.nextState(oldState, args, new CommandValue<>(id)));
+            state = newState;
+            if (!CommandValue.withValues(values, () -> command.postCondition(oldState, newState, args, result))) {
                 return CommandResult.fail(state, new Error("Postcondition failed"));
             }
             return CommandResult.success(state);
@@ -58,7 +58,7 @@ public class CommandList<State> {
             if (!command.preCondition(state, args)) {
                 return CommandResult.fail(state, new Error("Precondition failed"));
             }
-            state = command.nextState(state, args, new CommandValue.AbstractValue<>(id));
+            state = command.nextState(state, args, new CommandValue<>(id));
             return CommandResult.success(state);
         } catch (Throwable ex) {
             return CommandResult.fail(state, ex);
@@ -78,8 +78,14 @@ public class CommandList<State> {
 
     @Override
     public String toString() {
-        return "CommandList{" +
-                "commands=" + commands +
-                '}';
+        StringBuilder builder = new StringBuilder();
+        Iterator<GeneratedCommand<State, ?, ?>> iterator = commands.iterator();
+        while (iterator.hasNext()) {
+            builder.append(iterator.next());
+            if (iterator.hasNext()) {
+                builder.append(", ");
+            }
+        }
+        return builder.toString();
     }
 }
diff --git a/src/main/java/au/id/zancanaro/javacheck/statem/CommandListGenerator.java b/src/main/java/au/id/zancanaro/javacheck/state/CommandListGenerator.java
index a0df66f..4c2c47f 100644
--- a/src/main/java/au/id/zancanaro/javacheck/statem/CommandListGenerator.java
+++ b/src/main/java/au/id/zancanaro/javacheck/state/CommandListGenerator.java
@@ -1,4 +1,4 @@
-package au.id.zancanaro.javacheck.statem;
+package au.id.zancanaro.javacheck.state;
 
 import au.id.zancanaro.javacheck.Generator;
 import au.id.zancanaro.javacheck.ShrinkTree;
@@ -29,7 +29,7 @@ public class CommandListGenerator<State> implements Generator<CommandList<State>
     }
 
     public <Args, Result> State nextState(int id, GeneratedCommand<State, Args, Result> generatedCommand, State state) {
-        return generatedCommand.getCommand().nextState(state, generatedCommand.getArgs(), new CommandValue.AbstractValue<>(id));
+        return generatedCommand.getCommand().nextState(state, generatedCommand.getArgs(), new CommandValue<>(id));
     }
 
     @Override
diff --git a/src/main/java/au/id/zancanaro/javacheck/statem/CommandResult.java b/src/main/java/au/id/zancanaro/javacheck/state/CommandResult.java
index dc5b085..12f650d 100644
--- a/src/main/java/au/id/zancanaro/javacheck/statem/CommandResult.java
+++ b/src/main/java/au/id/zancanaro/javacheck/state/CommandResult.java
@@ -1,4 +1,4 @@
-package au.id.zancanaro.javacheck.statem;
+package au.id.zancanaro.javacheck.state;
 
 public class CommandResult<State> {
     private final State state;
diff --git a/src/main/java/au/id/zancanaro/javacheck/state/CommandValue.java b/src/main/java/au/id/zancanaro/javacheck/state/CommandValue.java
new file mode 100644
index 0000000..8d3f272
--- /dev/null
+++ b/src/main/java/au/id/zancanaro/javacheck/state/CommandValue.java
@@ -0,0 +1,47 @@
+package au.id.zancanaro.javacheck.state;
+
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.function.Supplier;
+
+public class CommandValue<T> {
+    private static Map<Integer, Object> values = null;
+
+    public static <T> T withValues(Map<Integer, Object> newValues, Supplier<T> action) {
+        Map<Integer,Object> oldValues = values;
+        try {
+            values = newValues;
+            return action.get();
+        } finally {
+            values = oldValues;
+        }
+    }
+
+    private final int id;
+
+    public CommandValue(int id) {
+        this.id = id;
+    }
+
+    public boolean isAbstract() {
+        return values == null;
+    }
+
+    @SuppressWarnings("unchecked")
+    public T get() {
+        if (values.containsKey(getId())) {
+            return (T) values.get(getId());
+        } else {
+            throw new NoSuchElementException("Concrete values cannot be supplied prior to being calculated");
+        }
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    @Override
+    public String toString() {
+        return "#{" + id + "}";
+    }
+}
diff --git a/src/main/java/au/id/zancanaro/javacheck/statem/GeneratedCommand.java b/src/main/java/au/id/zancanaro/javacheck/state/GeneratedCommand.java
index 5e576b4..90d9a47 100644
--- a/src/main/java/au/id/zancanaro/javacheck/statem/GeneratedCommand.java
+++ b/src/main/java/au/id/zancanaro/javacheck/state/GeneratedCommand.java
@@ -1,4 +1,4 @@
-package au.id.zancanaro.javacheck.statem;
+package au.id.zancanaro.javacheck.state;
 
 public class GeneratedCommand<State, Args, Result> {
     private final int id;
@@ -47,10 +47,6 @@ public class GeneratedCommand<State, Args, Result> {
 
     @Override
     public String toString() {
-        return "GeneratedCommand{" +
-                "id=" + id +
-                ", command=" + command +
-                ", args=" + args +
-                '}';
+        return "#{" + id + "} = " + command + " <- " + args;
     }
 }
diff --git a/src/main/java/au/id/zancanaro/javacheck/statem/CommandValue.java b/src/main/java/au/id/zancanaro/javacheck/statem/CommandValue.java
deleted file mode 100644
index 0a1fb61..0000000
--- a/src/main/java/au/id/zancanaro/javacheck/statem/CommandValue.java
+++ /dev/null
@@ -1,60 +0,0 @@
-package au.id.zancanaro.javacheck.statem;
-
-import java.util.Map;
-import java.util.NoSuchElementException;
-
-public abstract class CommandValue<T> {
-    private final int id;
-
-    public CommandValue(int id) {
-        this.id = id;
-    }
-
-    public abstract boolean isAbstract();
-
-    public abstract T get();
-
-    public int getId() {
-        return id;
-    }
-
-    static class AbstractValue<T> extends CommandValue<T> {
-        public AbstractValue(int id) {
-            super(id);
-        }
-
-        @Override
-        public boolean isAbstract() {
-            return true;
-        }
-
-        @Override
-        public T get() {
-            throw new NoSuchElementException("Abstract values cannot be supplied");
-        }
-    }
-
-    static class ConcreteValue<T> extends CommandValue<T> {
-        private final Map<Integer, Object> values;
-
-        public ConcreteValue(int id, Map<Integer, Object> values) {
-            super(id);
-            this.values = values;
-        }
-
-        @Override
-        public boolean isAbstract() {
-            return true;
-        }
-
-        @Override
-        @SuppressWarnings("unchecked")
-        public T get() {
-            if (values.containsKey(getId())) {
-                return (T) values.get(getId());
-            } else {
-                throw new NoSuchElementException("Concrete values cannot be supplied prior to being calculated");
-            }
-        }
-    }
-}
diff --git a/src/test/java/au/id/zancanaro/javacheck/state/queue/NewQueueCommand.java b/src/test/java/au/id/zancanaro/javacheck/state/queue/NewQueueCommand.java
new file mode 100644
index 0000000..d2815dc
--- /dev/null
+++ b/src/test/java/au/id/zancanaro/javacheck/state/queue/NewQueueCommand.java
@@ -0,0 +1,30 @@
+package au.id.zancanaro.javacheck.state.queue;
+
+import au.id.zancanaro.javacheck.state.Command;
+import au.id.zancanaro.javacheck.state.CommandValue;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class NewQueueCommand<T> extends Command<QueueState<T>, Void, Queue<T>> {
+    @Override
+    public boolean preCondition(QueueState<T> state, Void args) {
+        return state == null;
+    }
+
+    @Override
+    public Queue<T> runCommand(Void args) {
+        return new LinkedList<>();
+    }
+
+    @Override
+    public QueueState<T> nextState(QueueState<T> state, Void args, CommandValue<Queue<T>> result) {
+        return new QueueState<>(result, new ArrayList<>());
+    }
+
+    @Override
+    public String toString() {
+        return "new";
+    }
+}
diff --git a/src/test/java/au/id/zancanaro/javacheck/state/queue/PopQueueCommand.java b/src/test/java/au/id/zancanaro/javacheck/state/queue/PopQueueCommand.java
new file mode 100644
index 0000000..f8a018c
--- /dev/null
+++ b/src/test/java/au/id/zancanaro/javacheck/state/queue/PopQueueCommand.java
@@ -0,0 +1,58 @@
+package au.id.zancanaro.javacheck.state.queue;
+
+import au.id.zancanaro.javacheck.Generator;
+import au.id.zancanaro.javacheck.state.Command;
+import au.id.zancanaro.javacheck.state.CommandValue;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Queue;
+
+import static au.id.zancanaro.javacheck.Generator.pure;
+
+public class PopQueueCommand<T> extends Command<QueueState<T>, PopQueueCommand.ArgsType<T>, T> {
+    @Override
+    public Generator<ArgsType<T>> argsGenerator(QueueState<T> tQueueState) {
+        return pure(tQueueState.getConcreteQueue()).map(x -> new ArgsType<>(x));
+    }
+
+    @Override
+    public boolean preCondition(QueueState<T> state, ArgsType<T> args) {
+        return state != null && !state.getAbstractQueue().isEmpty();
+    }
+
+    @Override
+    public T runCommand(ArgsType<T> args) {
+        return args.queue.get().poll();
+    }
+
+    @Override
+    public QueueState<T> nextState(QueueState<T> state, ArgsType<T> args, CommandValue<T> result) {
+        List<T> newState = new ArrayList<>(state.getAbstractQueue());
+        newState.remove(0);
+        return new QueueState<>(state.getConcreteQueue(), newState);
+    }
+
+    @Override
+    public boolean postCondition(QueueState<T> oldState, QueueState<T> newState, ArgsType<T> args, T result) {
+        return oldState.getAbstractQueue().get(0) == result;
+    }
+
+    @Override
+    public String toString() {
+        return "pop";
+    }
+
+    static class ArgsType<T> {
+        public final CommandValue<Queue<T>> queue;
+
+        public ArgsType(CommandValue<Queue<T>> queue) {
+            this.queue = queue;
+        }
+
+        @Override
+        public String toString() {
+            return "[" + queue + "]";
+        }
+    }
+}
diff --git a/src/test/java/au/id/zancanaro/javacheck/state/queue/PushQueueCommand.java b/src/test/java/au/id/zancanaro/javacheck/state/queue/PushQueueCommand.java
new file mode 100644
index 0000000..b198eb5
--- /dev/null
+++ b/src/test/java/au/id/zancanaro/javacheck/state/queue/PushQueueCommand.java
@@ -0,0 +1,60 @@
+package au.id.zancanaro.javacheck.state.queue;
+
+import au.id.zancanaro.javacheck.Generator;
+import au.id.zancanaro.javacheck.state.Command;
+import au.id.zancanaro.javacheck.state.CommandValue;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Queue;
+
+public class PushQueueCommand<T> extends Command<QueueState<T>, PushQueueCommand.ArgsType<T>, Void> {
+    public final Generator<T> generator;
+
+    public PushQueueCommand(Generator<T> argGen) {
+        this.generator = argGen;
+    }
+
+    @Override
+    public Generator<ArgsType<T>> argsGenerator(QueueState<T> state) {
+        return generator.map(i -> new ArgsType<>(state.getConcreteQueue(), i));
+    }
+
+    @Override
+    public Void runCommand(ArgsType<T> args) {
+        args.queue.get().offer(args.pushValue);
+        return null;
+    }
+
+    @Override
+    public QueueState<T> nextState(QueueState<T> state, ArgsType<T> args, CommandValue<Void> result) {
+        List<T> newState = new ArrayList<>(state.getAbstractQueue());
+        newState.add(args.pushValue);
+        return new QueueState<>(state.getConcreteQueue(), newState);
+    }
+
+    @Override
+    public boolean preCondition(QueueState<T> state, ArgsType<T> args) {
+        return state != null;
+    }
+
+    @Override
+    public String toString() {
+        return "push";
+    }
+
+    static class ArgsType<T> {
+        public final CommandValue<Queue<T>> queue;
+        public final T pushValue;
+
+        public ArgsType(CommandValue<Queue<T>> queue, T pushValue) {
+            this.queue = queue;
+            this.pushValue = pushValue;
+        }
+
+        @Override
+        public String toString() {
+            return "[" + queue + ", " + pushValue + "]";
+        }
+    }
+}
diff --git a/src/test/java/au/id/zancanaro/javacheck/state/queue/QueueState.java b/src/test/java/au/id/zancanaro/javacheck/state/queue/QueueState.java
new file mode 100644
index 0000000..e4f65f8
--- /dev/null
+++ b/src/test/java/au/id/zancanaro/javacheck/state/queue/QueueState.java
@@ -0,0 +1,24 @@
+package au.id.zancanaro.javacheck.state.queue;
+
+import au.id.zancanaro.javacheck.state.CommandValue;
+
+import java.util.List;
+import java.util.Queue;
+
+public class QueueState<T> {
+    private final CommandValue<Queue<T>> concreteQueue;
+    private final List<T> abstractQueue;
+
+    public QueueState(CommandValue<Queue<T>> concreteQueue, List<T> abstractQueue) {
+        this.concreteQueue = concreteQueue;
+        this.abstractQueue = abstractQueue;
+    }
+
+    public CommandValue<Queue<T>> getConcreteQueue() {
+        return concreteQueue;
+    }
+
+    public List<T> getAbstractQueue() {
+        return abstractQueue;
+    }
+}
diff --git a/src/test/java/au/id/zancanaro/javacheck/state/queue/QueueTest.java b/src/test/java/au/id/zancanaro/javacheck/state/queue/QueueTest.java
new file mode 100644
index 0000000..083a8ad
--- /dev/null
+++ b/src/test/java/au/id/zancanaro/javacheck/state/queue/QueueTest.java
@@ -0,0 +1,37 @@
+package au.id.zancanaro.javacheck.state.queue;
+
+import au.id.zancanaro.javacheck.Generator;
+import au.id.zancanaro.javacheck.annotations.DataSource;
+import au.id.zancanaro.javacheck.annotations.Property;
+import au.id.zancanaro.javacheck.annotations.Seed;
+import au.id.zancanaro.javacheck.junit.Properties;
+import au.id.zancanaro.javacheck.state.*;
+import org.junit.runner.RunWith;
+
+import java.util.*;
+
+import static au.id.zancanaro.javacheck.Generator.pure;
+import static au.id.zancanaro.javacheck.Generators.integer;
+import static au.id.zancanaro.javacheck.Generators.oneOf;
+import static org.junit.Assert.assertFalse;
+
+@RunWith(Properties.class)
+public class QueueTest {
+    @DataSource
+    public static Generator<CommandList<QueueState<Integer>>> commandGenerator =
+            new CommandListGenerator<>(state ->
+                    state == null ?
+                            pure(new NewQueueCommand<>()) :
+                            oneOf(
+                                    pure(new PopQueueCommand<>()),
+                                    pure(new PushQueueCommand<>(integer()))
+                            ));
+
+    @Property
+    public void test(CommandList<QueueState<Integer>> commands) throws Throwable {
+        CommandResult<QueueState<Integer>> result = commands.run(null);
+        if (result.isFailed()) {
+            throw result.getThrown();
+        }
+    }
+}
diff --git a/src/test/java/au/id/zancanaro/javacheck/statem/QueueTest.java b/src/test/java/au/id/zancanaro/javacheck/statem/QueueTest.java
deleted file mode 100644
index 4cd6345..0000000
--- a/src/test/java/au/id/zancanaro/javacheck/statem/QueueTest.java
+++ /dev/null
@@ -1,88 +0,0 @@
-package au.id.zancanaro.javacheck.statem;
-
-import au.id.zancanaro.javacheck.Generator;
-import au.id.zancanaro.javacheck.annotations.DataSource;
-import au.id.zancanaro.javacheck.annotations.Property;
-import au.id.zancanaro.javacheck.junit.Properties;
-import org.junit.runner.RunWith;
-
-import java.util.*;
-
-import static au.id.zancanaro.javacheck.Generator.pure;
-import static au.id.zancanaro.javacheck.Generators.integer;
-import static au.id.zancanaro.javacheck.Generators.oneOf;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-
-@RunWith(Properties.class)
-public class QueueTest {
-    private static final Queue<Integer> queue = new LinkedList<>();
-
-    @DataSource
-    public static Generator<CommandList<List<Integer>>> commandGenerator =
-            new CommandListGenerator<>(state -> oneOf(
-                    pure(new QueuePushCommand()),
-                    pure(new QueuePopCommand())
-            ));
-
-    @Property
-    public void test(CommandList<List<Integer>> commands) {
-        queue.clear();
-        CommandResult<List<Integer>> result = commands.run(null);
-        assertFalse(result.isFailed());
-    }
-
-    private static class QueuePushCommand extends Command<List<Integer>, Integer, Void> {
-        @Override
-        public Generator<Integer> argsGenerator(List<Integer> integers) {
-            return integer();
-        }
-
-        @Override
-        public Void runCommand(Integer integer) {
-            queue.offer(integer);
-            return null;
-        }
-
-        @Override
-        public List<Integer> nextState(List<Integer> integers, Integer integer, CommandValue<Void> result) {
-            List<Integer> nextState = new ArrayList<>(integers == null ? new ArrayList<>() : integers);
-            nextState.add(integer);
-            return nextState;
-        }
-
-        @Override
-        public String toString() {
-            return "push";
-        }
-    }
-
-    private static class QueuePopCommand extends Command<List<Integer>, Void, Integer> {
-        @Override
-        public boolean preCondition(List<Integer> integers, Void aVoid) {
-            return integers != null && !integers.isEmpty();
-        }
-
-        @Override
-        public Integer runCommand(Void aVoid) {
-            return queue.poll();
-        }
-
-        @Override
-        public boolean postCondition(List<Integer> oldState, List<Integer> newState, Void aVoid, Integer integer) {
-            return Objects.equals(integer, oldState.get(0));
-        }
-
-        @Override
-        public List<Integer> nextState(List<Integer> integers, Void aVoid, CommandValue<Integer> result) {
-            List<Integer> nextState = new ArrayList<>(integers == null ? new ArrayList<>() : integers);
-            nextState.remove(0);
-            return nextState;
-        }
-
-        @Override
-        public String toString() {
-            return "pop";
-        }
-    }
-}