CSV-252: Clean up exception handling (apache#50)

* CSV-252: Clean up assertions using assertThrows

As a followup to commit e2f0a4d that
introduced JUnit Jupiter to the project, this patch leverages the new
Assertions#assertThrows method to clean up tests for expected
exceptions.

Instead of the somewhat clunky structure common in JUnit 4 tests:

```
try {
    someMethod();
    fail("SomeException should be thrown");
} catch (SomeException e) {
    // Expected...

    // Possibly some assertion on e
}
```

JUnit Jupiter allows the following elegant syntax:

```
SomeException e = assertThrows(SomeException.class, () -> someMethod());
// Possibly some assertions on e
```

* CSV-252: Remove redundant throws clauses from tests

Author: mureinik

src/test/java/org/apache/commons/csv/AssertionsTest.java

@@ -26,7 +26,7 @@
 public class AssertionsTest {
 
     @Test
-    public void testNotNull() throws Exception {
+    public void testNotNull() {
         Assertions.notNull(new Object(), "object");
     }
 

src/test/java/org/apache/commons/csv/CSVBenchmark.java

@@ -67,7 +67,7 @@ public void init() throws IOException {
         in.close();
     }
 
-    private BufferedReader getReader() throws IOException {
+    private BufferedReader getReader() {
         return new BufferedReader(new StringReader(data));
     }
 

src/test/java/org/apache/commons/csv/CSVFormatTest.java

@@ -550,17 +550,12 @@ public void testFormatThrowsNullPointerException() {
 
         final CSVFormat csvFormat = CSVFormat.MYSQL;
 
-        try {
-            csvFormat.format((Object[]) null);
-            fail("Expecting exception: NullPointerException");
-        } catch(final NullPointerException e) {
-            assertEquals(CSVFormat.class.getName(), e.getStackTrace()[0].getClassName());
-        }
-
+        NullPointerException e = assertThrows(NullPointerException.class, () -> csvFormat.format((Object[]) null));
+        assertEquals(CSVFormat.class.getName(), e.getStackTrace()[0].getClassName());
     }
 
     @Test
-    public void testGetHeader() throws Exception {
+    public void testGetHeader() {
         final String[] header = new String[]{"one", "two", "three"};
         final CSVFormat formatWithHeader = CSVFormat.DEFAULT.withHeader(header);
         // getHeader() makes a copy of the header array.
@@ -893,7 +888,7 @@ public void testToStringAndWithCommentMarkerTakingCharacter() {
     }
 
     @Test
-    public void testWithCommentStart() throws Exception {
+    public void testWithCommentStart() {
         final CSVFormat formatWithCommentStart = CSVFormat.DEFAULT.withCommentMarker('#');
         assertEquals( Character.valueOf('#'), formatWithCommentStart.getCommentMarker());
     }
@@ -904,7 +899,7 @@ public void testWithCommentStartCRThrowsException() {
     }
 
     @Test
-    public void testWithDelimiter() throws Exception {
+    public void testWithDelimiter() {
         final CSVFormat formatWithDelimiter = CSVFormat.DEFAULT.withDelimiter('!');
         assertEquals('!', formatWithDelimiter.getDelimiter());
     }
@@ -915,13 +910,13 @@ public void testWithDelimiterLFThrowsException() {
     }
 
     @Test
-    public void testWithEmptyEnum() throws Exception {
+    public void testWithEmptyEnum() {
         final CSVFormat formatWithHeader = CSVFormat.DEFAULT.withHeader(EmptyEnum.class);
         assertTrue(formatWithHeader.getHeader().length == 0);
     }
 
     @Test
-    public void testWithEscape() throws Exception {
+    public void testWithEscape() {
         final CSVFormat formatWithEscape = CSVFormat.DEFAULT.withEscape('&');
         assertEquals(Character.valueOf('&'), formatWithEscape.getEscapeCharacter());
     }
@@ -932,14 +927,14 @@ public void testWithEscapeCRThrowsExceptions() {
     }
 
     @Test
-    public void testWithFirstRecordAsHeader() throws Exception {
+    public void testWithFirstRecordAsHeader() {
         final CSVFormat formatWithFirstRecordAsHeader = CSVFormat.DEFAULT.withFirstRecordAsHeader();
         assertTrue(formatWithFirstRecordAsHeader.getSkipHeaderRecord());
         assertTrue(formatWithFirstRecordAsHeader.getHeader().length == 0);
     }
 
     @Test
-    public void testWithHeader() throws Exception {
+    public void testWithHeader() {
         final String[] header = new String[]{"one", "two", "three"};
         // withHeader() makes a copy of the header array.
         final CSVFormat formatWithHeader = CSVFormat.DEFAULT.withHeader(header);
@@ -1111,35 +1106,35 @@ public void testWithHeaderComments() {
 
 
     @Test
-    public void testWithHeaderEnum() throws Exception {
+    public void testWithHeaderEnum() {
         final CSVFormat formatWithHeader = CSVFormat.DEFAULT.withHeader(Header.class);
         assertArrayEquals(new String[]{ "Name", "Email", "Phone" }, formatWithHeader.getHeader());
     }
 
 
     @Test
-    public void testWithIgnoreEmptyLines() throws Exception {
+    public void testWithIgnoreEmptyLines() {
         assertFalse(CSVFormat.DEFAULT.withIgnoreEmptyLines(false).getIgnoreEmptyLines());
         assertTrue(CSVFormat.DEFAULT.withIgnoreEmptyLines().getIgnoreEmptyLines());
     }
 
 
     @Test
-    public void testWithIgnoreSurround() throws Exception {
+    public void testWithIgnoreSurround() {
         assertFalse(CSVFormat.DEFAULT.withIgnoreSurroundingSpaces(false).getIgnoreSurroundingSpaces());
         assertTrue(CSVFormat.DEFAULT.withIgnoreSurroundingSpaces().getIgnoreSurroundingSpaces());
     }
 
 
     @Test
-    public void testWithNullString() throws Exception {
+    public void testWithNullString() {
         final CSVFormat formatWithNullString = CSVFormat.DEFAULT.withNullString("null");
         assertEquals("null", formatWithNullString.getNullString());
     }
 
 
     @Test
-    public void testWithQuoteChar() throws Exception {
+    public void testWithQuoteChar() {
         final CSVFormat formatWithQuoteChar = CSVFormat.DEFAULT.withQuote('"');
         assertEquals(Character.valueOf('"'), formatWithQuoteChar.getQuoteCharacter());
     }
@@ -1151,31 +1146,31 @@ public void testWithQuoteLFThrowsException() {
     }
 
     @Test
-    public void testWithQuotePolicy() throws Exception {
+    public void testWithQuotePolicy() {
         final CSVFormat formatWithQuotePolicy = CSVFormat.DEFAULT.withQuoteMode(QuoteMode.ALL);
         assertEquals(QuoteMode.ALL, formatWithQuotePolicy.getQuoteMode());
     }
 
     @Test
-    public void testWithRecordSeparatorCR() throws Exception {
+    public void testWithRecordSeparatorCR() {
         final CSVFormat formatWithRecordSeparator = CSVFormat.DEFAULT.withRecordSeparator(CR);
         assertEquals(String.valueOf(CR), formatWithRecordSeparator.getRecordSeparator());
     }
 
     @Test
-    public void testWithRecordSeparatorCRLF() throws Exception {
+    public void testWithRecordSeparatorCRLF() {
         final CSVFormat formatWithRecordSeparator = CSVFormat.DEFAULT.withRecordSeparator(CRLF);
         assertEquals(CRLF, formatWithRecordSeparator.getRecordSeparator());
     }
 
     @Test
-    public void testWithRecordSeparatorLF() throws Exception {
+    public void testWithRecordSeparatorLF() {
         final CSVFormat formatWithRecordSeparator = CSVFormat.DEFAULT.withRecordSeparator(LF);
         assertEquals(String.valueOf(LF), formatWithRecordSeparator.getRecordSeparator());
     }
 
     @Test
-    public void testWithSystemRecordSeparator() throws Exception {
+    public void testWithSystemRecordSeparator() {
         final CSVFormat formatWithRecordSeparator = CSVFormat.DEFAULT.withSystemRecordSeparator();
         assertEquals(System.getProperty("line.separator"), formatWithRecordSeparator.getRecordSeparator());
     }

src/test/java/org/apache/commons/csv/CSVParserTest.java

@@ -27,7 +27,6 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assertions.fail;
 
 import java.io.File;
 import java.io.IOException;
@@ -529,12 +528,7 @@ public void testGetHeaderNamesReadOnly() throws IOException {
             CSVFormat.DEFAULT.withHeader("A", "B", "C"))) {
             final List<String> headerNames = parser.getHeaderNames();
             assertNotNull(headerNames);
-            try {
-                headerNames.add("This is a read-only list.");
-                fail();
-            } catch (final UnsupportedOperationException e) {
-                // Yes.
-            }
+            assertThrows(UnsupportedOperationException.class, () -> headerNames.add("This is a read-only list."));
         }
     }
 
@@ -758,12 +752,7 @@ public void testIterator() throws Exception {
         final Iterator<CSVRecord> iterator = CSVFormat.DEFAULT.parse(in).iterator();
 
         assertTrue(iterator.hasNext());
-        try {
-            iterator.remove();
-            fail("expected UnsupportedOperationException");
-        } catch (final UnsupportedOperationException expected) {
-            // expected
-        }
+        assertThrows(UnsupportedOperationException.class, iterator::remove);
         assertArrayEquals(new String[] { "a", "b", "c" }, iterator.next().values());
         assertArrayEquals(new String[] { "1", "2", "3" }, iterator.next().values());
         assertTrue(iterator.hasNext());
@@ -772,12 +761,7 @@ public void testIterator() throws Exception {
         assertArrayEquals(new String[] { "x", "y", "z" }, iterator.next().values());
         assertFalse(iterator.hasNext());
 
-        try {
-            iterator.next();
-            fail("NoSuchElementException expected");
-        } catch (final NoSuchElementException e) {
-            // expected
-        }
+        assertThrows(NoSuchElementException.class, iterator::next);
     }
 
     @Test