Allow Uniqueness.by() to return more specific function type

jqwik-team · Jun 10, 2024 · 485960d · 485960d
1 parent a3cea7d
commit 485960d
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Showing 5 changed files with 22 additions and 20 deletions.
diff --git a/api/src/main/java/net/jqwik/api/constraints/UniqueElements.java b/api/src/main/java/net/jqwik/api/constraints/UniqueElements.java
@@ -4,6 +4,7 @@
 import java.util.function.*;
 
 import org.apiguardian.api.*;
+import org.jspecify.annotations.*;
 
 import static org.apiguardian.api.API.Status.*;
 
@@ -30,5 +31,5 @@ public Object apply(Object o) {
 			throw new IllegalArgumentException("This class must not be used");
 		}
 	}
-	Class<? extends Function<?, Object>> by() default NOT_SET.class;
+	Class<? extends Function<? extends @Nullable Object, ?>> by() default NOT_SET.class;
 }
diff --git a/documentation/src/test/java/net/jqwik/docs/UniquenessExamples.java b/documentation/src/test/java/net/jqwik/docs/UniquenessExamples.java
@@ -46,9 +46,9 @@ void listOfStringsTheFirstCharacterOfWhichMustBeUnique(
 		Assertions.assertThat(firstCharacters).doesNotHaveDuplicates();
 	}
 
-	private class FirstChar implements Function<String, Object> {
+	private class FirstChar implements Function<String, Character> {
 		@Override
-		public Object apply(String aString) {
+		public Character apply(String aString) {
 			return aString.charAt(0);
 		}
 	}

diff --git a/...e/src/main/java/net/jqwik/engine/properties/configurators/UniqueElementsConfigurator.java b/...e/src/main/java/net/jqwik/engine/properties/configurators/UniqueElementsConfigurator.java
@@ -17,7 +17,7 @@
 @SuppressWarnings("unchecked")
 public class UniqueElementsConfigurator implements ArbitraryConfigurator {
 
-	@SuppressWarnings("OverlyComplexMethod")
+	@SuppressWarnings({"OverlyComplexMethod", "OverlyLongMethod"})
 	@Override
 	public <T extends @Nullable Object> Arbitrary<T> configure(Arbitrary<T> arbitrary, TypeUsage targetType) {
 		return targetType.findAnnotation(UniqueElements.class).map(uniqueness -> {
@@ -66,8 +66,9 @@ public class UniqueElementsConfigurator implements ArbitraryConfigurator {
 		return list;
 	}
 
+	@SuppressWarnings("OverlyLongMethod")
 	private static <C extends Collection<?>> Predicate<C> isUnique(UniqueElements uniqueness) {
-		Class<? extends Function<?, Object>> extractorClass = uniqueness.by();
+		Class<? extends Function<?, ?>> extractorClass = uniqueness.by();
 		if (extractorClass.equals(UniqueElements.NOT_SET.class)) {
 			return items -> {
 				// Intentionally uses `items.getClass().equals(HashSet.class)`
@@ -101,7 +102,7 @@ private static <C extends Collection<?>> Predicate<C> isUnique(UniqueElements un
 	}
 
 	private <T extends @Nullable Object> Arbitrary<?> configureStreamableArbitrary(StreamableArbitrary<T, ?> arbitrary, UniqueElements uniqueness) {
-		Class<? extends Function<?, Object>> extractorClass = uniqueness.by();
+		Class<? extends Function<?, ?>> extractorClass = uniqueness.by();
 		if (extractorClass.equals(UniqueElements.NOT_SET.class)) {
 			return arbitrary.uniqueElements();
 		}
@@ -110,15 +111,15 @@ private static <C extends Collection<?>> Predicate<C> isUnique(UniqueElements un
 	}
 
 	private <T extends @Nullable Object> Arbitrary<?> configureSetArbitrary(SetArbitrary<T> arbitrary, UniqueElements uniqueness) {
-		Class<? extends Function<?, Object>> extractorClass = uniqueness.by();
+		Class<? extends Function<?, ?>> extractorClass = uniqueness.by();
 		if (extractorClass.equals(UniqueElements.NOT_SET.class)) {
 			return arbitrary;
 		}
 		Function<T, Object> extractor = extractor(extractorClass);
 		return arbitrary.uniqueElements(extractor);
 	}
 
-	private static <T extends @Nullable Object> Function<T, Object> extractor(Class<? extends Function<?, Object>> extractorClass) {
+	private static <T extends @Nullable Object> Function<T, Object> extractor(Class<? extends Function<?, ?>> extractorClass) {
 		return (Function<T, Object>) (
 			extractorClass.equals(UniqueElements.NOT_SET.class)
 				? Function.identity()

diff --git a/engine/src/test/java/net/jqwik/api/constraints/UniqueElementsProperties.java b/engine/src/test/java/net/jqwik/api/constraints/UniqueElementsProperties.java
@@ -27,9 +27,9 @@ boolean listsOfModuloIntegers(@ForAll @UniqueElements(by = Modulo13.class) List<
 			return hasNoDuplicates(integerList, i -> i % 13);
 		}
 
-		private class Modulo13 implements Function<Integer, Object> {
+		private class Modulo13 implements Function<Integer, Integer> {
 			@Override
-			public Object apply(Integer integer) {
+			public Integer apply(Integer integer) {
 				return integer % 13;
 			}
 		}
@@ -102,9 +102,9 @@ private Set<String> asSet(String... strings) {
 			return new LinkedHashSet<>(asList(strings));
 		}
 
-		private class GetFirstTwoChars implements Function<String, Object> {
+		private class GetFirstTwoChars implements Function<String, String> {
 			@Override
-			public Object apply(String string) {
+			public String apply(String string) {
 				return string.substring(0, 2);
 			}
 		}
@@ -202,9 +202,9 @@ private List<String> toList(Iterator<String> iterator) {
 
 	}
 
-	private class GetStringLength implements Function<String, Object> {
+	private class GetStringLength implements Function<String, Integer> {
 		@Override
-		public Object apply(String string) {
+		public Integer apply(String string) {
 			return string.length();
 		}
 	}

diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinUniqueElementsConfigurator.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinUniqueElementsConfigurator.kt
@@ -17,11 +17,11 @@ class KotlinUniqueElementsConfigurator : ArbitraryConfigurator {
             return@map when {
                 arbitrary is SequenceArbitrary<*> -> configureSequenceArbitrary(arbitrary, uniqueness)
                 targetType.isAssignableFrom(Sequence::class) -> {
-                    val sequenceArbitrary = arbitrary as Arbitrary<Sequence<*>>
+                    val sequenceArbitrary = arbitrary as Arbitrary<Sequence<T>>
                     sequenceArbitrary.filter {
                         isUnique(
                             it.toList(),
-                            extractor(uniqueness) as Function<Any?, Any>
+                            extractor<T>(uniqueness) as Function<Any?, Any>
                         )
                     }
                 }
@@ -40,13 +40,13 @@ class KotlinUniqueElementsConfigurator : ArbitraryConfigurator {
         arbitrary: SequenceArbitrary<T>,
         uniqueness: UniqueElements
     ): SequenceArbitrary<T> {
-        val extractor = extractor(uniqueness) as Function<T, Any>
+        val extractor = extractor<T>(uniqueness) as Function<T?, *>
         return arbitrary.uniqueElements(extractor)
     }
 
-    private fun extractor(uniqueElements: UniqueElements): Function<*, Any> {
-        val extractorClass: Class<out Function<*, Any>> = uniqueElements.by.java
-        return if (extractorClass == NOT_SET::class.java) Function.identity()
+    private fun <T> extractor(uniqueElements: UniqueElements): Function<*, *> {
+        val extractorClass: Class<out Function<*, *>> = uniqueElements.by.java
+        return if (extractorClass == NOT_SET::class.java) Function.identity<Any>()
         // TODO: Create instance in context of test instance.
         //       This requires an extension of ArbitraryConfiguration interface
         //       to provide access to PropertyLifecycleContext