Generalise the ObjectGeneration stuff

The new ObjectGeneration stuff is now used to generate everything for a test
case, which means it's all unified and "nice" now.

Add a @UseGenerator annotation to be used to specify how to generate specific
field values.

Obviously, not everything can be generated magically, so if you specify a
@DataSource in your test then it will be used in preference to any magically
generated value.

15 files changed, 82 insertions, 100 deletions

diff --git a/src/main/java/au/id/zancanaro/javacheck/DataSourceHelper.java b/src/main/java/au/id/zancanaro/javacheck/DataSourceHelper.java
index 522fd26..f118649 100644
--- a/src/main/java/au/id/zancanaro/javacheck/DataSourceHelper.java
+++ b/src/main/java/au/id/zancanaro/javacheck/DataSourceHelper.java
@@ -3,10 +3,11 @@ package au.id.zancanaro.javacheck;
 import au.id.zancanaro.javacheck.annotations.DataSource;
 
 import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
-import java.util.*;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
 
 public class DataSourceHelper {
     private final Class<?> classObject;
@@ -17,47 +18,6 @@ public class DataSourceHelper {
         this.generators = new HashMap<>();
     }
 
-    public static Set<Type> validateGeneratorFields(Class<?> classObject, List<Throwable> errors) {
-        Set<Type> result = new HashSet<>();
-
-        for (Field field : classObject.getDeclaredFields()) {
-            if (field.isAnnotationPresent(DataSource.class)) {
-                boolean error = false;
-                if (!Modifier.isStatic(field.getModifiers())) {
-                    errors.add(new Error("@DataSource field " + field.getName() + " must be static"));
-                    error = true;
-                }
-                if (!Modifier.isPublic(field.getModifiers())) {
-                    errors.add(new Error("@DataSource field " + field.getName() + " must be public"));
-                    error = true;
-                }
-
-                Type type = field.getGenericType();
-                ParameterizedType parameterizedType;
-                if (type instanceof ParameterizedType) {
-                    parameterizedType = (ParameterizedType) type;
-                    if (parameterizedType.getRawType() instanceof Class) {
-                        Class<?> c = (Class) parameterizedType.getRawType();
-                        if (c == Generator.class) {
-                            if (!error) {
-                                result.add(parameterizedType.getActualTypeArguments()[0]);
-                            }
-                        } else {
-                            errors.add(new Error("@DataSource fields must be of type Generator<T>"));
-                        }
-                    } else {
-                        errors.add(new Error("@DataSource fields must be of type Generator<T>"));
-                    }
-                } else {
-                    errors.add(new Error("@DataSource fields must be of type Generator<T>"));
-                }
-            }
-        }
-
-        return result;
-    }
-
-
     private static final Map<Type, Type> rawTypes;
 
     static {
diff --git a/src/main/java/au/id/zancanaro/javacheck/junit/Properties.java b/src/main/java/au/id/zancanaro/javacheck/junit/Properties.java
index 94032bc..a7bf19b 100644
--- a/src/main/java/au/id/zancanaro/javacheck/junit/Properties.java
+++ b/src/main/java/au/id/zancanaro/javacheck/junit/Properties.java
@@ -1,11 +1,11 @@
 package au.id.zancanaro.javacheck.junit;
 
-import au.id.zancanaro.javacheck.DataSourceHelper;
 import au.id.zancanaro.javacheck.Generator;
 import au.id.zancanaro.javacheck.ShrinkResult;
 import au.id.zancanaro.javacheck.ShrinkTree;
 import au.id.zancanaro.javacheck.annotations.Property;
 import au.id.zancanaro.javacheck.annotations.Seed;
+import au.id.zancanaro.javacheck.object.GeneratorProvider;
 import org.junit.AssumptionViolatedException;
 import org.junit.runners.BlockJUnit4ClassRunner;
 import org.junit.runners.model.FrameworkMethod;
@@ -13,38 +13,24 @@ import org.junit.runners.model.InitializationError;
 import org.junit.runners.model.Statement;
 import org.junit.runners.model.TestClass;
 
+import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
-import java.lang.reflect.Type;
 import java.util.*;
 
 @SuppressWarnings("WeakerAccess")
 public class Properties extends BlockJUnit4ClassRunner {
-    private final DataSourceHelper helper;
+    private final GeneratorProvider provider;
 
     public Properties(Class<?> classObject) throws InitializationError {
         super(classObject);
-        helper = new DataSourceHelper(classObject);
+        provider = GeneratorProvider.DEFAULT_PROVIDER.withDataSources(classObject);
     }
 
     @Override
     protected void collectInitializationErrors(List<Throwable> errors) {
         super.collectInitializationErrors(errors);
-        Set<Type> generated = DataSourceHelper.validateGeneratorFields(getTestClass().getJavaClass(), errors);
-        validateTestMethodParameters(errors, generated);
     }
 
-    private void validateTestMethodParameters(List<Throwable> errors, Set<Type> generated) {
-        for (FrameworkMethod each : computeTestMethods()) {
-            for (Type type : each.getMethod().getGenericParameterTypes()) {
-                if (!generated.contains(type)) {
-                    errors.add(new Error("No @DataSource for type: " + type));
-                    generated.add(type); // ignore future errors on this type
-                }
-            }
-        }
-    }
-
-
     @Override
     protected void validateConstructor(List<Throwable> errors) {
         validateOnlyOneConstructor(errors);
@@ -73,18 +59,18 @@ public class Properties extends BlockJUnit4ClassRunner {
 
     @Override
     public Statement methodBlock(final FrameworkMethod method) {
-        return new GenerativeTester(method, getTestClass(), helper.computeGenerators());
+        return new GenerativeTester(method, getTestClass(), provider);
     }
 
     public static class GenerativeTester extends Statement {
         private final FrameworkMethod testMethod;
         private final TestClass testClass;
-        private final Map<Type, Generator<?>> generators;
+        private final GeneratorProvider provider;
 
-        public GenerativeTester(FrameworkMethod testMethod, TestClass testClass, Map<Type, Generator<?>> generators) {
+        public GenerativeTester(FrameworkMethod testMethod, TestClass testClass, GeneratorProvider provider) {
             this.testMethod = testMethod;
             this.testClass = testClass;
-            this.generators = generators;
+            this.provider = provider;
         }
 
         private static long getSeed(Method method) {
@@ -103,7 +89,7 @@ public class Properties extends BlockJUnit4ClassRunner {
                 runTest(new Object[0]);
             } else {
                 Generator<?>[] generators = Arrays.stream(method.getGenericParameterTypes())
-                        .map(this.generators::get)
+                        .map(param -> provider.getGenerator(param, new Annotation[0], provider))
                         .toArray(Generator[]::new);
                 Generator<List<Object>> generator = Generator.tuple(generators);
 
@@ -126,7 +112,6 @@ public class Properties extends BlockJUnit4ClassRunner {
                             throw new Error("Violated 50 assumptions in a row: failing test");
                         }
                     } catch (Throwable ex) {
-//                        tree.print(new OutputStreamWriter(System.out), Arrays::toString);
                         throw new PropertyError(method.getName(), seed, shrink(tree, ex));
                     }
                 }
@@ -178,8 +163,7 @@ public class Properties extends BlockJUnit4ClassRunner {
         public void runTest(final Object[] args) throws Throwable {
             new BlockJUnit4ClassRunner(testClass.getJavaClass()) {
                 @Override
-                protected void collectInitializationErrors(
-                        List<Throwable> errors) {
+                protected void collectInitializationErrors(List<Throwable> errors) {
                     // do nothing
                 }
 
diff --git a/src/main/java/au/id/zancanaro/javacheck/junit/PropertyError.java b/src/main/java/au/id/zancanaro/javacheck/junit/PropertyError.java
index d3747b9..5f89ca8 100644
--- a/src/main/java/au/id/zancanaro/javacheck/junit/PropertyError.java
+++ b/src/main/java/au/id/zancanaro/javacheck/junit/PropertyError.java
@@ -2,7 +2,6 @@ package au.id.zancanaro.javacheck.junit;
 
 import au.id.zancanaro.javacheck.ShrinkResult;
 
-import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
 
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/CharType.java b/src/main/java/au/id/zancanaro/javacheck/object/CharType.java
index befbd04..aa3049e 100644
--- a/src/main/java/au/id/zancanaro/javacheck/object/CharType.java
+++ b/src/main/java/au/id/zancanaro/javacheck/object/CharType.java
@@ -5,7 +5,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Target(ElementType.FIELD)
+@Target({ElementType.FIELD, ElementType.PARAMETER})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface CharType {
     public static enum TYPE {
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/DoubleRange.java b/src/main/java/au/id/zancanaro/javacheck/object/DoubleRange.java
index ca7c9a9..08f8e3a 100644
--- a/src/main/java/au/id/zancanaro/javacheck/object/DoubleRange.java
+++ b/src/main/java/au/id/zancanaro/javacheck/object/DoubleRange.java
@@ -5,7 +5,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Target(ElementType.FIELD)
+@Target({ElementType.FIELD, ElementType.PARAMETER})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface DoubleRange {
     double min();
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/GeneratorProvider.java b/src/main/java/au/id/zancanaro/javacheck/object/GeneratorProvider.java
index 7e5964f..67769b6 100644
--- a/src/main/java/au/id/zancanaro/javacheck/object/GeneratorProvider.java
+++ b/src/main/java/au/id/zancanaro/javacheck/object/GeneratorProvider.java
@@ -1,8 +1,10 @@
 package au.id.zancanaro.javacheck.object;
 
+import au.id.zancanaro.javacheck.DataSourceHelper;
 import au.id.zancanaro.javacheck.Generator;
 
 import java.lang.annotation.Annotation;
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
@@ -28,7 +30,14 @@ public interface GeneratorProvider {
 
         @Override
         public Generator<?> getGenerator(Type type, Annotation[] annotations, GeneratorProvider provider) {
-            if (type == Integer.TYPE || type == Integer.class) {
+            UseGenerator generator = getAnnotation(annotations, UseGenerator.class);
+            if (generator != null) {
+                try {
+                    return generator.value().getConstructor().newInstance();
+                } catch (InvocationTargetException | NoSuchMethodException | InstantiationException | IllegalAccessException ex) {
+                    throw new ObjectGenerationException("Could not construct generator of type " + generator.value(), ex);
+                }
+            } else if (type == Integer.TYPE || type == Integer.class) {
                 IntRange range = getAnnotation(annotations, IntRange.class);
                 if (range == null) {
                     return integer();
@@ -50,11 +59,11 @@ public interface GeneratorProvider {
                     return doublePrecision(range.min(), range.max());
                 }
             } else if (type == String.class) {
-                CharType range = getAnnotation(annotations, CharType.class);
-                if (range == null) {
+                CharType charType = getAnnotation(annotations, CharType.class);
+                if (charType == null) {
                     return string();
                 } else {
-                    switch (range.value()) {
+                    switch (charType.value()) {
                         case ALPHA:
                             return stringOf(alphaCharacter());
                         case ALPHA_NUMERIC:
@@ -114,4 +123,16 @@ public interface GeneratorProvider {
             }
         };
     }
+
+    default GeneratorProvider withDataSources(Class<?> wrappingType) {
+        DataSourceHelper helper = new DataSourceHelper(wrappingType);
+        Map<Type, Generator<?>> generators = helper.computeGenerators();
+        return (type, annotations, provider) -> {
+            if (generators.containsKey(type)) {
+                return generators.get(type);
+            } else {
+                return this.getGenerator(type, annotations, provider);
+            }
+        };
+    }
 }
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/IntRange.java b/src/main/java/au/id/zancanaro/javacheck/object/IntRange.java
index 8dc3f28..5d2aa30 100644
--- a/src/main/java/au/id/zancanaro/javacheck/object/IntRange.java
+++ b/src/main/java/au/id/zancanaro/javacheck/object/IntRange.java
@@ -5,7 +5,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Target(ElementType.FIELD)
+@Target({ElementType.FIELD, ElementType.PARAMETER})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface IntRange {
     int max();
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/LongRange.java b/src/main/java/au/id/zancanaro/javacheck/object/LongRange.java
index dd5a61f..dd5b8cf 100644
--- a/src/main/java/au/id/zancanaro/javacheck/object/LongRange.java
+++ b/src/main/java/au/id/zancanaro/javacheck/object/LongRange.java
@@ -5,7 +5,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Target(ElementType.FIELD)
+@Target({ElementType.FIELD, ElementType.PARAMETER})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface LongRange {
     long max();
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/ObjectGenerationException.java b/src/main/java/au/id/zancanaro/javacheck/object/ObjectGenerationException.java
index d2147eb..444de32 100644
--- a/src/main/java/au/id/zancanaro/javacheck/object/ObjectGenerationException.java
+++ b/src/main/java/au/id/zancanaro/javacheck/object/ObjectGenerationException.java
@@ -8,4 +8,8 @@ public class ObjectGenerationException extends RuntimeException {
     public ObjectGenerationException(Throwable cause) {
         super(cause);
     }
+
+    public ObjectGenerationException(String message, Throwable cause) {
+        super(message, cause);
+    }
 }
diff --git a/src/main/java/au/id/zancanaro/javacheck/object/UseGenerator.java b/src/main/java/au/id/zancanaro/javacheck/object/UseGenerator.java
new file mode 100644
index 0000000..f62d978
--- /dev/null
+++ b/src/main/java/au/id/zancanaro/javacheck/object/UseGenerator.java
@@ -0,0 +1,14 @@
+package au.id.zancanaro.javacheck.object;
+
+import au.id.zancanaro.javacheck.Generator;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.FIELD, ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface UseGenerator {
+    Class<? extends Generator> value();
+}
diff --git a/src/test/java/au/id/zancanaro/javacheck/ListFunctorRulesTest.java b/src/test/java/au/id/zancanaro/javacheck/ListFunctorRulesTest.java
index b757bcd..4100378 100644
--- a/src/test/java/au/id/zancanaro/javacheck/ListFunctorRulesTest.java
+++ b/src/test/java/au/id/zancanaro/javacheck/ListFunctorRulesTest.java
@@ -9,7 +9,8 @@ import java.util.List;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
-import static au.id.zancanaro.javacheck.Generators.*;
+import static au.id.zancanaro.javacheck.Generators.longInteger;
+import static au.id.zancanaro.javacheck.Generators.oneOf;
 import static org.junit.Assert.assertEquals;
 
 @RunWith(Properties.class)
@@ -19,9 +20,6 @@ public class ListFunctorRulesTest {
     private final static int maxSize = 1000;
 
     @DataSource
-    public static Generator<List<Long>> listOfIntegers = listOf(longInteger());
-
-    @DataSource
     public static Generator<Function<Long, Long>> integerFunction =
             oneOf(
                     longInteger().map(ListFunctorRulesTest::plusI),
diff --git a/src/test/java/au/id/zancanaro/javacheck/SimpleListOperationsTest.java b/src/test/java/au/id/zancanaro/javacheck/SimpleListOperationsTest.java
index fcc8baf..3f4d58b 100644
--- a/src/test/java/au/id/zancanaro/javacheck/SimpleListOperationsTest.java
+++ b/src/test/java/au/id/zancanaro/javacheck/SimpleListOperationsTest.java
@@ -1,6 +1,5 @@
 package au.id.zancanaro.javacheck;
 
-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;
@@ -8,7 +7,6 @@ import org.junit.runner.RunWith;
 import java.util.ArrayList;
 import java.util.List;
 
-import static au.id.zancanaro.javacheck.Generators.*;
 import static java.util.Collections.reverse;
 import static java.util.Collections.sort;
 import static org.junit.Assert.assertEquals;
@@ -19,12 +17,6 @@ public class SimpleListOperationsTest {
     private final static int runs = 1000;
     private final static int maxSize = 1000;
 
-    @DataSource
-    public static Generator<List<Integer>> listOfIntegers = listOf(integer());
-
-    @DataSource
-    public static Generator<List<String>> listOfStrings = listOf(stringOf(alphaNumericCharacter()));
-
     @Property(maxSize = maxSize, runs = runs)
     public void sortingIsIdempotent(List<Integer> list) {
         List<Integer> left = new ArrayList<>(list);
diff --git a/src/test/java/au/id/zancanaro/javacheck/object/MyObject.java b/src/test/java/au/id/zancanaro/javacheck/object/MyObject.java
index ac0c370..824fd8d 100644
--- a/src/test/java/au/id/zancanaro/javacheck/object/MyObject.java
+++ b/src/test/java/au/id/zancanaro/javacheck/object/MyObject.java
@@ -1,5 +1,13 @@
 package au.id.zancanaro.javacheck.object;
 
+import au.id.zancanaro.javacheck.Generator;
+import au.id.zancanaro.javacheck.ShrinkTree;
+
+import java.util.Random;
+
+import static au.id.zancanaro.javacheck.Generators.asciiCharacter;
+import static au.id.zancanaro.javacheck.Generators.stringOf;
+
 public class MyObject {
     public final String string;
     public final int value;
@@ -12,10 +20,21 @@ public class MyObject {
     }
 
     @UseForGeneration
-    public MyObject(String string, SubObject<Integer> subObject) {
+    public MyObject(
+            @UseGenerator(StringGenerator.class) String string,
+            SubObject<Integer> subObject) {
         this(string, string.length(), subObject);
     }
 
+    public static class StringGenerator implements Generator<String> {
+        public final Generator<String> gen = stringOf(asciiCharacter());
+
+        @Override
+        public ShrinkTree<String> generate(Random random, int size) {
+            return gen.generate(random, size);
+        }
+    }
+
     public MyObject add(MyObject other) {
         return new MyObject(
                 this.string + other.string,
diff --git a/src/test/java/au/id/zancanaro/javacheck/object/MyObjectAddTest.java b/src/test/java/au/id/zancanaro/javacheck/object/MyObjectAddTest.java
index 7965449..9321acb 100644
--- a/src/test/java/au/id/zancanaro/javacheck/object/MyObjectAddTest.java
+++ b/src/test/java/au/id/zancanaro/javacheck/object/MyObjectAddTest.java
@@ -1,23 +1,15 @@
 package au.id.zancanaro.javacheck.object;
 
-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.Collections;
-
-import static au.id.zancanaro.javacheck.Generators.ofType;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(Properties.class)
 public class MyObjectAddTest {
 
-    @DataSource
-    public static Generator<MyObject> source = ofType(MyObject.class);
-
     @Property
     public void testAdd(MyObject a, MyObject b) {
         MyObject added = a.add(b);
diff --git a/src/test/java/au/id/zancanaro/javacheck/state/queue/commands/Offer.java b/src/test/java/au/id/zancanaro/javacheck/state/queue/commands/Offer.java
index 301efeb..366e974 100644
--- a/src/test/java/au/id/zancanaro/javacheck/state/queue/commands/Offer.java
+++ b/src/test/java/au/id/zancanaro/javacheck/state/queue/commands/Offer.java
@@ -7,7 +7,6 @@ import au.id.zancanaro.javacheck.state.queue.QueueState;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Queue;
 
 public class Offer<T> extends Command<QueueState<T>, T, Void> {
     public final Generator<T> generator;