Issue #64 - Add Factory/Supplier support

Author: boretti

src/main/java/ch/powerunit/extensions/exceptions/CommonsCollections4Helper.java

@@ -19,11 +19,12 @@
  */
 package ch.powerunit.extensions.exceptions;
 
+import static ch.powerunit.extensions.exceptions.Constants.verifySupplier;
 import static ch.powerunit.extensions.exceptions.Constants.verifyPredicate;
 
 import java.util.function.Function;
-import java.util.function.Predicate;
 
+import org.apache.commons.collections4.Factory;
 import org.apache.commons.collections4.FunctorException;
 
 /**
@@ -68,4 +69,25 @@ private CommonsCollections4Helper() {
 	public static <T> org.apache.commons.collections4.Predicate<T> asPredicate(PredicateWithException<T, ?> predicate) {
 		return PredicateWithException.unchecked(verifyPredicate(predicate), DEFAULT_EXCEPTION_MAPPER)::test;
 	}
+
+	/**
+	 * Transforms a {@link SupplierWithException} to the one from
+	 * commons-collections.
+	 * 
+	 * @param supplier
+	 *            the {@link SupplierWithException} to be transformed to the one
+	 *            from commons-collections.
+	 * @param <T>
+	 *            the type of the result of the supplier
+	 * @return the {@link Factory factory} from commons-collections. The exception
+	 *         are wrapped in a FunctorException.
+	 * @throws NoClassDefFoundError
+	 *             In case the commons-collections4 library is not available.
+	 * @throws NullPointerException
+	 *             if supplier is null.
+	 * @see org.apache.commons.collections4.Factory
+	 */
+	public static <T> Factory<T> asFactory(SupplierWithException<T, ?> supplier) {
+		return SupplierWithException.unchecked(verifySupplier(supplier), FunctorException::new)::get;
+	}
 }

src/test/java/ch/powerunit/extensions/exceptions/CommonsCollections4HelperTest.java

@@ -25,6 +25,8 @@
 @SuppressWarnings("squid:S2187") // Sonar doesn't under that it is really a test
 public class CommonsCollections4HelperTest implements TestSuite {
 
+	// AsPredicate
+
 	@Test
 	public void testAsPredicateNoException() {
 		assertThat(CommonsCollections4Helper.asPredicate(x -> true).evaluate("x")).is(true);
@@ -49,4 +51,17 @@ public void testAsPredicateOtherException() {
 				.evaluate("x")).throwException(instanceOf(Exception.class));
 	}
 
+	// AsFactory
+
+	@Test
+	public void testAsFactoryNoException() {
+		assertThat(CommonsCollections4Helper.asFactory(() -> "").create()).is("");
+	}
+
+	@Test
+	public void testAsFactoryOtherException() {
+		assertWhen(() -> CommonsCollections4Helper.asFactory(SupplierWithException.failing(Exception::new)).create())
+				.throwException(instanceOf(Exception.class));
+	}
+
 }