Introduce unit tests for ArgumentsAccessor

Issue: #1370

Author: sbrannen

junit-jupiter-params/src/main/java/org/junit/jupiter/params/aggregator/DefaultArgumentsAccessor.java

@@ -19,6 +19,7 @@
 
 import org.apiguardian.api.API;
 import org.junit.jupiter.params.converter.DefaultArgumentConverter;
+import org.junit.platform.commons.util.ClassUtils;
 import org.junit.platform.commons.util.Preconditions;
 
 /**
@@ -36,7 +37,7 @@ public class DefaultArgumentsAccessor implements ArgumentsAccessor {
 
 	private final Object[] arguments;
 
-	public DefaultArgumentsAccessor(Object[] arguments) {
+	public DefaultArgumentsAccessor(Object... arguments) {
 		Preconditions.notNull(arguments, "Arguments array must not be null");
 		this.arguments = arguments;
 	}
@@ -56,8 +57,10 @@ public <T> T get(int index, Class<T> requiredType) {
 			Object convertedValue = DefaultArgumentConverter.INSTANCE.convert(value, requiredType);
 			return requiredType.cast(convertedValue);
 		}
-		catch (ClassCastException ex) {
-			String message = format("Argument [%s] at index [%d] could not be converted or cast to [%s]", value, index,
+		catch (Exception ex) {
+			String message = format(
+				"Argument at index [%d] with value [%s] and type [%s] could not be converted or cast to type [%s].",
+				index, value, ClassUtils.nullSafeToString(value == null ? null : value.getClass()),
 				requiredType.getName());
 			throw new ArgumentsAccessorException(message, ex);
 		}

junit-jupiter-params/src/test/java/org/junit/jupiter/params/aggregator/ArgumentsAccessorTests.java

@@ -0,0 +1,152 @@
+/*
+ * Copyright 2015-2018 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.jupiter.params.aggregator;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertIterableEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import org.junit.platform.commons.util.PreconditionViolationException;
+
+/**
+ * Unit tests for {@link ArgumentsAccessor}.
+ *
+ * @since 5.2
+ */
+class ArgumentsAccessorTests {
+
+	@Test
+	void preconditions() {
+		assertThrows(PreconditionViolationException.class, () -> new DefaultArgumentsAccessor((Object[]) null));
+
+		ArgumentsAccessor arguments = new DefaultArgumentsAccessor(1, 2);
+		Exception exception = assertThrows(PreconditionViolationException.class, () -> arguments.get(-1));
+		assertThat(exception.getMessage()).isEqualTo("index must be >= 0 and < 2");
+	}
+
+	@Test
+	void getNull() {
+		assertNull(new DefaultArgumentsAccessor(new Object[] { null }).get(0));
+	}
+
+	@Test
+	void getWithNullCastToWrapperType() {
+		assertNull(new DefaultArgumentsAccessor((Object[]) new Integer[] { null }).get(0, Integer.class));
+	}
+
+	@Test
+	void get() {
+		assertEquals(1, new DefaultArgumentsAccessor(1).get(0));
+	}
+
+	@Test
+	void getWithCast() {
+		assertEquals(Integer.valueOf(1), new DefaultArgumentsAccessor(1).get(0, Integer.class));
+		assertEquals(Character.valueOf('A'), new DefaultArgumentsAccessor('A').get(0, Character.class));
+	}
+
+	@Test
+	void getWithCastToPrimitiveType() {
+		Exception exception = assertThrows(ArgumentsAccessorException.class,
+			() -> new DefaultArgumentsAccessor(1).get(0, int.class));
+		assertThat(exception.getMessage()).isEqualTo(
+			"Argument at index [0] with value [1] and type [java.lang.Integer] could not be converted or cast to type [int].");
+	}
+
+	@Test
+	void getWithCastToIncompatibleType() {
+		Exception exception = assertThrows(ArgumentsAccessorException.class,
+			() -> new DefaultArgumentsAccessor(1).get(0, Character.class));
+		assertThat(exception.getMessage()).isEqualTo(
+			"Argument at index [0] with value [1] and type [java.lang.Integer] could not be converted or cast to type [java.lang.Character].");
+	}
+
+	@Test
+	void getCharacter() {
+		assertEquals(Character.valueOf('A'), new DefaultArgumentsAccessor('A', 'B').getCharacter(0));
+	}
+
+	@Test
+	void getBoolean() {
+		assertEquals(Boolean.TRUE, new DefaultArgumentsAccessor(true, false).getBoolean(0));
+	}
+
+	@Test
+	void getByte() {
+		assertEquals(Byte.valueOf((byte) 42), new DefaultArgumentsAccessor((byte) 42).getByte(0));
+	}
+
+	@Test
+	void getShort() {
+		assertEquals(Short.valueOf((short) 42), new DefaultArgumentsAccessor((short) 42).getShort(0));
+	}
+
+	@Test
+	void getInteger() {
+		assertEquals(Integer.valueOf(42), new DefaultArgumentsAccessor(42).getInteger(0));
+	}
+
+	@Test
+	void getLong() {
+		assertEquals(Long.valueOf(42L), new DefaultArgumentsAccessor(42L).getLong(0));
+	}
+
+	@Test
+	void getFloat() {
+		assertEquals(Float.valueOf(42.0f), new DefaultArgumentsAccessor(42.0f).getFloat(0));
+	}
+
+	@Test
+	void getDouble() {
+		assertEquals(Double.valueOf(42.0), new DefaultArgumentsAccessor(42.0).getDouble(0));
+	}
+
+	@Test
+	void getString() {
+		assertEquals("foo", new DefaultArgumentsAccessor("foo", "bar").getString(0));
+	}
+
+	@Test
+	void toArray() {
+		DefaultArgumentsAccessor arguments = new DefaultArgumentsAccessor("foo", "bar");
+		Object[] copy = arguments.toArray();
+		assertArrayEquals(new String[] { "foo", "bar" }, copy);
+
+		// Modify local copy:
+		copy[0] = "Boom!";
+		assertEquals("foo", arguments.toArray()[0]);
+	}
+
+	@Test
+	void toList() {
+		DefaultArgumentsAccessor arguments = new DefaultArgumentsAccessor("foo", "bar");
+		List<Object> copy = arguments.toList();
+		assertIterableEquals(Arrays.asList("foo", "bar"), copy);
+
+		// Modify local copy:
+		assertThrows(UnsupportedOperationException.class, () -> copy.set(0, "Boom!"));
+	}
+
+	@Test
+	void size() {
+		assertEquals(0, new DefaultArgumentsAccessor().size());
+		assertEquals(1, new DefaultArgumentsAccessor(42).size());
+		assertEquals(5, new DefaultArgumentsAccessor('a', 'b', 'c', 'd', 'e').size());
+	}
+
+}