Added test cases for error handling.

sort_four_pairs/src/test/java/edu/unl/cse/soft160/sort_four_pairs/SortFourPairsTest.java

@@ -7,6 +7,7 @@ import junit.framework.TestSuite;
 import java.io.InputStream;
 import java.io.ByteArrayInputStream;
 import java.io.PrintStream;
+import java.security.Permission;
 import java.io.ByteArrayOutputStream;
 
 public class SortFourPairsTest extends TestCase {
@@ -34,6 +35,64 @@ public class SortFourPairsTest extends TestCase {
 		return collector.toString();
 	}
 
+	@SuppressWarnings("serial")
+	protected static class ExitException extends SecurityException {
+		public final int status;
+
+		public ExitException(int status) {
+			super("Exit with status " + status);
+			this.status = status;
+		}
+	}
+
+	private static class TestingSecurityManager extends SecurityManager {
+		@Override
+		public void checkPermission(Permission perm) {
+		}
+
+		@Override
+		public void checkPermission(Permission perm, Object context) {
+		}
+
+		@Override
+		public void checkExit(int status) {
+			super.checkExit(status);
+			throw new ExitException(status);
+		}
+	}
+
+	@Override
+	protected void setUp() throws Exception {
+		super.setUp();
+		System.setSecurityManager(new TestingSecurityManager());
+	}
+
+	@Override
+	protected void tearDown() throws Exception {
+		System.setSecurityManager(null);
+		super.tearDown();
+	}
+
+	protected static String runMainForError(int expectedStatus, String... arguments) {
+		InputStream in = System.in;
+		PrintStream err = System.err;
+		System.setIn(new ByteArrayInputStream("".getBytes()));
+		ByteArrayOutputStream collector = new ByteArrayOutputStream();
+		System.setErr(new PrintStream(collector));
+		boolean exited = false;
+		try {
+			SortFourPairs.main(arguments);
+		} catch (ExitException expected) {
+			assertEquals(expectedStatus, expected.status);
+			exited = true;
+		} finally {
+			System.setIn(in);
+			System.setErr(err);
+		}
+		assertTrue(exited);
+		return collector.toString();
+	}
+
 	public void testZeros() {
 		assertEquals(assemble("(0.0, 0.0)", "(0.0, 0.0)", "(0.0, 0.0)", "(0.0, 0.0)"),
 				runMain("0", "0", "0", "0", "0", "0", "0", "0"));
@@ -188,4 +247,18 @@ public class SortFourPairsTest extends TestCase {
 		assertEquals(assemble("(0.0, 0.0)", "(1.0, 1.0)", "(2.0, 2.0)", "(3.0, 3.0)"),
 				runMain("1", "1", "0", "0", "2", "2", "3", "3"));
 	}
+
+	public void testTooFewArguments() {
+		assertEquals(
+				assemble("Sorts four points, by their x coordinates, breaking ties using y coordinates.",
+						"Usage: [Program] [X0] [Y0] [X1] [Y1] [X2] [Y2] [X3] [Y3]"),
+				runMainForError(1, "0", "0", "1", "1", "2", "2", "3"));
+	}
+
+	public void testNonNumericArguments() {
+		assertEquals(
+				assemble("Sorts four points, by their x coordinates, breaking ties using y coordinates.",
+						"Usage: [Program] [X0] [Y0] [X1] [Y1] [X2] [Y2] [X3] [Y3]"),
+				runMainForError(1, "0", "0", "1", "1", "2", "2", "3", "Three"));
+	}
 }