Add unit test for ccsdk/core

*Add a unit test for SliStringUtils
This is to test substring method of SliStringUtils
and improve code coverage

Issue-Id: CCSDK-106
Change-Id: I73c5af3b036a92fdcb1d3d1be7eb0b3abc44fd5a
Signed-off-by: surya-huawei <a.u.surya@huawei.com>
diff --git a/sliPluginUtils/provider/src/test/java/org/onap/ccsdk/sli/core/slipluginutils/SliStringUtilsTest.java b/sliPluginUtils/provider/src/test/java/org/onap/ccsdk/sli/core/slipluginutils/SliStringUtilsTest.java
index 96c6ae4..4fc8d18 100644
--- a/sliPluginUtils/provider/src/test/java/org/onap/ccsdk/sli/core/slipluginutils/SliStringUtilsTest.java
+++ b/sliPluginUtils/provider/src/test/java/org/onap/ccsdk/sli/core/slipluginutils/SliStringUtilsTest.java
@@ -91,6 +91,18 @@
     }
 
     @Test
+    public final void testSubString() throws SvcLogicException {
+        param.put("string","splitatgivenindex");
+        param.put("begin-index","0");
+        param.put("end-index","5");
+        param.put("result","result");
+
+        stringUtils.substring(param, ctx);
+
+        assertEquals("split", ctx.getAttribute("result"));
+    }
+
+    @Test
     public final void testQuotedOrNull() throws SvcLogicException {
         //param.put("nullString",null);
         assertEquals("NULL",SliStringUtils.quotedOrNULL(null));