more exclusion of non-existing directories

Author: StevenArzt

soot-infoflow-summaries/test/soot/jimple/infoflow/test/methodSummary/junit/TestHelper.java

@@ -56,10 +56,29 @@ public static void setUp() throws IOException {
 		if (!(testSrc1.exists() || testSrc2.exists()))
 			fail("Test aborted - none of the test sources are available");
 
-		appPath = testSrc1.getCanonicalPath() + sep + testSrc2.getCanonicalPath();
+		StringBuilder appPathBuilder = new StringBuilder();
+		appendWithSeparator(appPathBuilder, testSrc1);
+		appendWithSeparator(appPathBuilder, testSrc2);
+		appPath = appPathBuilder.toString();
+
 		libPath = System.getProperty("java.home") + File.separator + "lib" + File.separator + "rt.jar";
 	}
 
+	/**
+	 * Appends the given path to the given {@link StringBuilder} if it exists
+	 * 
+	 * @param sb The {@link StringBuilder} to which to append the path
+	 * @param f  The path to append
+	 * @throws IOException
+	 */
+	private static void appendWithSeparator(StringBuilder sb, File f) throws IOException {
+		if (f.exists()) {
+			if (sb.length() > 0)
+				sb.append(System.getProperty("path.separator"));
+			sb.append(f.getCanonicalPath());
+		}
+	}
+
 	protected boolean containsFlow(Set<MethodFlow> flows, SourceSinkType sourceTyp, String[] sourceFields,
 			SourceSinkType sinkTyp, String[] sinkFields) {
 		return containsFlow(flows, sourceTyp, -1, sourceFields, sinkTyp, -1, sinkFields);