Add some more interesting tests

3 files changed, 42 insertions, 3 deletions

diff --git a/src/main/java/au/id/zancanaro/javacheck/Generator.java b/src/main/java/au/id/zancanaro/javacheck/Generator.java
index c28d967..557cf97 100644
--- a/src/main/java/au/id/zancanaro/javacheck/Generator.java
+++ b/src/main/java/au/id/zancanaro/javacheck/Generator.java
@@ -1,5 +1,6 @@
 package au.id.zancanaro.javacheck;
 
+import java.util.Iterator;
 import java.util.List;
 import java.util.Random;
 import java.util.function.Function;
@@ -128,4 +129,8 @@ public interface Generator<T> {
     default <R> Generator<R> flatMap(Function<T, Generator<R>> action) {
         return (random, size) -> RoseTree.join(this.generate(random, size).map(action).map(g -> g.generate(random, size)));
     }
+
+    default Iterator<T> sample(Random random, int maxSize) {
+        return new GeneratorSampleIterator<>(this, random, maxSize);
+    }
 }
diff --git a/src/main/java/au/id/zancanaro/javacheck/GeneratorSampleIterator.java b/src/main/java/au/id/zancanaro/javacheck/GeneratorSampleIterator.java
new file mode 100644
index 0000000..f7d8e17
--- /dev/null
+++ b/src/main/java/au/id/zancanaro/javacheck/GeneratorSampleIterator.java
@@ -0,0 +1,30 @@
+package au.id.zancanaro.javacheck;
+
+import java.util.Iterator;
+import java.util.Random;
+
+public class GeneratorSampleIterator<T> implements Iterator<T> {
+    private final Generator<T> generator;
+    private final Random random;
+    private final int maxSize;
+    private int size;
+
+    public GeneratorSampleIterator(Generator<T> generator, Random random, int maxSize) {
+        this.generator = generator;
+        this.random = random;
+        this.maxSize = maxSize;
+        this.size = 0;
+    }
+
+    @Override
+    public boolean hasNext() {
+        return true;
+    }
+
+    @Override
+    public T next() {
+        return generator
+                .generate(random, Math.min(size++, maxSize))
+                .getValue();
+    }
+}
diff --git a/src/main/java/au/id/zancanaro/javacheck/Generators.java b/src/main/java/au/id/zancanaro/javacheck/Generators.java
index 548bd29..4049149 100644
--- a/src/main/java/au/id/zancanaro/javacheck/Generators.java
+++ b/src/main/java/au/id/zancanaro/javacheck/Generators.java
@@ -91,10 +91,12 @@ public final class Generators {
         return (random, size) -> {
             Generator<Integer> countGen = sized(s -> integer(minElements, maxElements));
             int count = countGen.generate(random, size).getValue();
-            return Generator.list(count, gen).generate(random, size)
+            return Generator.list(count, gen)
+                    .generate(random, size)
                     .filter(list ->
                             minElements <= list.size()
-                                    && list.size() < maxElements);
+                                    && list.size() < maxElements)
+                    .map(Collections::unmodifiableList);
         };
     }
 
@@ -102,7 +104,9 @@ public final class Generators {
         return (random, size) -> {
             Generator<Integer> countGen = sized(s -> integer(0, s));
             int count = countGen.generate(random, size).getValue();
-            return Generator.list(count, gen).generate(random, size);
+            return Generator.list(count, gen)
+                    .generate(random, size)
+                    .map(Collections::unmodifiableList);
         };
     }