Add @DataSource, allow printing of RoseTrees, other small changes to generators

5 files changed, 94 insertions, 20 deletions

diff --git a/src/main/java/au/id/zancanaro/Generators.java b/src/main/java/au/id/zancanaro/Generators.java
index e0927ff..01ab64a 100644
--- a/src/main/java/au/id/zancanaro/Generators.java
+++ b/src/main/java/au/id/zancanaro/Generators.java
@@ -1,11 +1,17 @@
 package au.id.zancanaro;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.function.Function;
 import java.util.function.Predicate;
 
 public class Generators {
+    public static <T> Generator<T> sized(Function<Integer, Generator<T>> makeGenerator) {
+        return (random, size) -> makeGenerator.apply(size).generate(random, size);
+    }
+
     public static <T> Generator<T> suchThat(Generator<T> gen, Predicate<T> pred) {
         return (random, size) -> {
             RoseTree<T> result = gen.generate(random, size);
@@ -22,6 +28,13 @@ public class Generators {
         return integer(0, gens.length).flatMap(index -> gens[index]);
     }
 
+    public static Generator<Boolean> bool() {
+        return (random, size) ->
+                random.nextBoolean() ?
+                        new RoseTree<>(true, Collections.singletonList(new RoseTree<>(false, Collections.emptyList()))) :
+                        new RoseTree<>(false, Collections.emptyList());
+    }
+
     public static Generator<Integer> integer(int lower, int upper) {
         return (random, size) -> {
             int value = lower + random.nextInt(upper - lower);
@@ -31,11 +44,11 @@ public class Generators {
     }
 
     public static Generator<Integer> integer() {
-        return (random, size) -> integer(-size, size).generate(random, size);
+        return sized(size -> integer(-size, size));
     }
 
     public static Generator<Integer> natural() {
-        return (random, size) -> integer(0, size).generate(random, size);
+        return sized(size -> integer(0, size));
     }
 
     private static Iterable<RoseTree<Integer>> intShrinkingIterable(final int value, final int bound) {
@@ -57,11 +70,11 @@ public class Generators {
     }
 
     public static <T> Generator<List<T>> listOf(Generator<T> gen) {
-        return (random, size) -> integer(0, size).flatMap(count -> {
+        return (Generator<List<T>>) sized(size -> {
             @SuppressWarnings("unchecked")
-            Generator<T>[] gens = (Generator<T>[]) new Generator[count];
+            Generator<T>[] gens = (Generator<T>[]) new Generator[size];
             Arrays.fill(gens, gen);
-            return Generator.tuple(gens).fmap(Arrays::asList);
-        }).generate(random, size);
+            return Generator.tuple(gens).fmap(Arrays::asList).fmap(Collections::unmodifiableList);
+        });
     }
 }
diff --git a/src/main/java/au/id/zancanaro/Properties.java b/src/main/java/au/id/zancanaro/Properties.java
index fab48f4..b5a0649 100644
--- a/src/main/java/au/id/zancanaro/Properties.java
+++ b/src/main/java/au/id/zancanaro/Properties.java
@@ -1,5 +1,6 @@
 package au.id.zancanaro;
 
+import au.id.zancanaro.annotations.DataSource;
 import au.id.zancanaro.annotations.Property;
 import au.id.zancanaro.annotations.Seed;
 import org.junit.AssumptionViolatedException;
@@ -14,7 +15,7 @@ import java.util.*;
 
 
 public class Properties extends BlockJUnit4ClassRunner {
-    private final Map<Type, Generator<Object>> generators = new HashMap<>();
+    private final Map<Type, Generator<?>> generators = new HashMap<>();
 
     public Properties(Class<?> klass) throws InitializationError {
         super(klass);
@@ -23,13 +24,18 @@ public class Properties extends BlockJUnit4ClassRunner {
     @Override
     protected void collectInitializationErrors(List<Throwable> errors) {
         super.collectInitializationErrors(errors);
-        validateGeneratorFields(errors);
+        Set<Type> generated = validateGeneratorFields(errors);
+        validateTestMethodParameters(errors, generated);
     }
 
-    private void validateGeneratorFields(List<Throwable> errors) {
+    private Set<Type> validateGeneratorFields(List<Throwable> errors) {
+        Set<Type> result = new HashSet<>();
         Field[] fields = getTestClass().getJavaClass().getDeclaredFields();
 
         for (Field field : fields) {
+            if (!field.isAnnotationPresent(DataSource.class)) {
+                continue;
+            }
             Type type = field.getGenericType();
             if (!(type instanceof ParameterizedType)) {
                 continue;
@@ -42,11 +48,29 @@ public class Properties extends BlockJUnit4ClassRunner {
             if (c != Generator.class) {
                 continue;
             }
+            boolean error = false;
             if (!Modifier.isStatic(field.getModifiers())) {
                 errors.add(new Error("Generator field " + field.getName() + " must be static"));
+                error = true;
             }
             if (!Modifier.isPublic(field.getModifiers())) {
                 errors.add(new Error("Generator field " + field.getName() + " must be public"));
+                error = true;
+            }
+            if (!error) {
+                result.add(ptype.getActualTypeArguments()[0]);
+            }
+        }
+        return result;
+    }
+
+    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
+                }
             }
         }
     }
@@ -66,11 +90,14 @@ public class Properties extends BlockJUnit4ClassRunner {
         rawTypes = Collections.unmodifiableMap(types);
     }
 
-    private Map<Type, Generator<Object>> computeGenerators() {
+    private Map<Type, Generator<?>> computeGenerators() {
         if (generators.isEmpty()) {
             Field[] fields = getTestClass().getJavaClass().getDeclaredFields();
 
             for (Field field : fields) {
+                if (!field.isAnnotationPresent(DataSource.class)) {
+                    continue;
+                }
                 Type type = field.getGenericType();
                 if (!(type instanceof ParameterizedType)) {
                     continue;
@@ -133,9 +160,9 @@ public class Properties extends BlockJUnit4ClassRunner {
     public static class GenerativeTester extends Statement {
         private final FrameworkMethod testMethod;
         private final TestClass testClass;
-        private final Map<Type, Generator<Object>> generators;
+        private final Map<Type, Generator<?>> generators;
 
-        public GenerativeTester(FrameworkMethod testMethod, TestClass testClass, Map<Type, Generator<Object>> generators) {
+        public GenerativeTester(FrameworkMethod testMethod, TestClass testClass, Map<Type, Generator<?>> generators) {
             this.testMethod = testMethod;
             this.testClass = testClass;
             this.generators = generators;
@@ -157,12 +184,14 @@ public class Properties extends BlockJUnit4ClassRunner {
                 runTest(new Object[0]);
             } else {
                 @SuppressWarnings("unchecked")
-                Generator<Object>[] generators = (Generator<Object>[]) new Generator[method.getParameterCount()];
+                Generator<?>[] generators = (Generator<?>[]) new Generator[method.getParameterCount()];
                 int index = 0;
                 for (Type type : method.getGenericParameterTypes()) {
+                    // TODO: validate ahead of time that this generator will exist (ideally in the constructor validation time)
                     generators[index++] = this.generators.get(type);
                 }
-                Generator<Object[]> generator = Generator.tuple(generators);
+                @SuppressWarnings("unchecked")
+                Generator<Object[]> generator = Generator.tuple((Generator<Object>[]) generators);
 
                 long seed = getSeed(method);
                 Random random = new Random(seed);
@@ -184,6 +213,7 @@ public class Properties extends BlockJUnit4ClassRunner {
                         }
                         ;
                     } catch (Throwable ex) {
+//                        tree.print(new OutputStreamWriter(System.out), Arrays::toString);
                         throw new PropertyError(method.getName(), seed, shrink(tree, ex));
                     }
                 }
diff --git a/src/main/java/au/id/zancanaro/PropertyError.java b/src/main/java/au/id/zancanaro/PropertyError.java
index b2fb589..a0ee6df 100644
--- a/src/main/java/au/id/zancanaro/PropertyError.java
+++ b/src/main/java/au/id/zancanaro/PropertyError.java
@@ -6,10 +6,14 @@ import java.util.Iterator;
 
 public class PropertyError extends AssertionError {
     public PropertyError(String methodName, long seed, ShrinkResult shrunk) {
-        super(String.format("%s(%s)\n\tSeed: %s\n%s",
-                methodName, join(", ", shrunk.args),
-                seed,
-                shrunk.thrown.getMessage()));
+        super(shrunk.thrown.getMessage() == null ?
+                String.format("%s(%s)\n\tSeed: %s",
+                        methodName, join(", ", shrunk.args),
+                        seed):
+                String.format("%s(%s)\n\tSeed: %s\n%s",
+                        methodName, join(", ", shrunk.args),
+                        seed,
+                        shrunk.thrown.getMessage()));
         initCause(shrunk.thrown);
     }
 
diff --git a/src/main/java/au/id/zancanaro/RoseTree.java b/src/main/java/au/id/zancanaro/RoseTree.java
index 6ba5c1c..458d441 100644
--- a/src/main/java/au/id/zancanaro/RoseTree.java
+++ b/src/main/java/au/id/zancanaro/RoseTree.java
@@ -1,7 +1,7 @@
 package au.id.zancanaro;
 
-import java.io.OutputStream;
-import java.util.Arrays;
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.function.Function;
@@ -84,4 +84,20 @@ public class RoseTree<T> {
             throw new IllegalArgumentException("Current value doesn't match predicate: whoops!");
         }
     }
+
+    @SuppressWarnings("unused")
+    public void print(Writer output) throws IOException {
+        print(output, Object::toString);
+    }
+
+    @SuppressWarnings("unused")
+    public void print(Writer output, Function<T, String> toString) throws IOException {
+        output.write(toString.apply(this.getValue()));
+        output.write('[');
+        for (RoseTree<T> child : children) {
+            child.print(output, toString);
+        }
+        output.write(']');
+        output.flush();
+    }
 }
diff --git a/src/main/java/au/id/zancanaro/annotations/DataSource.java b/src/main/java/au/id/zancanaro/annotations/DataSource.java
new file mode 100644
index 0000000..9fe255b
--- /dev/null
+++ b/src/main/java/au/id/zancanaro/annotations/DataSource.java
@@ -0,0 +1,11 @@
+package au.id.zancanaro.annotations;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.FIELD})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface DataSource {
+}