diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListenerTest.java
index cb4c42d..ab84306 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/ConfigListenerTest.java
@@ -129,19 +129,6 @@
     }
 
     /**
-     * Checks config statement as sub-statement of module.
-     */
-    @Test
-    public void processModuleSubStatementConfig() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("mismatched input 'config' expecting {'anyxml', 'augment', 'choice', 'contact', "
-                + "'container', 'description', 'extension', 'deviation', 'feature', 'grouping', 'identity', 'import',"
-                + " 'include', 'leaf', 'leaf-list', 'list', 'notification', 'organization', 'reference',"
-                + " 'revision', 'rpc', 'typedef', 'uses', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/ModuleSubStatementConfig.yang");
-    }
-
-    /**
      * Checks config statement as sub-statement of container.
      */
     @Test
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java
index a5b2dfb..b156188 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListListenerTest.java
@@ -91,13 +91,8 @@
     /**
      * Checks whether exception is thrown when leaf-list keyword is incorrect.
      */
-    @Test
+    @Test(expected = ParserException.class)
     public void processLeafListInvalidStatement() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("mismatched input 'leaflist' expecting {'anyxml', 'augment', 'choice', 'contact', "
-                + "'container', 'description', 'extension', 'deviation', 'feature', 'grouping', 'identity', 'import',"
-                + " 'include', 'leaf', 'leaf-list', 'list', 'notification', 'organization', 'reference',"
-                + " 'revision', 'rpc', 'typedef', 'uses', '}'}");
         YangNode node = manager.getDataModel("src/test/resources/LeafListInvalidStatement.yang");
     }
 
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java
index 0b4beaa..9bbd0f5 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/LeafListenerTest.java
@@ -90,19 +90,6 @@
     }
 
     /**
-     * Checks whether exception is thrown when leaf keyword is incorrect.
-     */
-    @Test
-    public void processLeafInvalidStatement() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("mismatched input 'leafs' expecting {'anyxml', 'augment', 'choice', 'contact', "
-                + "'container', 'description', 'extension', 'deviation', 'feature', 'grouping', 'identity', 'import',"
-                + " 'include', 'leaf', 'leaf-list', 'list', 'notification', 'organization', 'reference',"
-                + " 'revision', 'rpc', 'typedef', 'uses', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/LeafInvalidStatement.yang");
-    }
-
-    /**
      * Checks whether exception is thrown when leaf keyword without Left brace
      * as per grammar.
      */
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListenerTest.java
index 52e43a9..fef5599 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MandatoryListenerTest.java
@@ -140,18 +140,4 @@
         thrown.expectMessage("missing ';' at '}'");
         YangNode node = manager.getDataModel("src/test/resources/MandatoryWithoutStatementEnd.yang");
     }
-
-    /**
-     * Checks mandatory statement as sub-statement of module and expects
-     * exception.
-     */
-    @Test
-    public void processModuleSubStatementMandatory() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("mismatched input 'mandatory' expecting {'anyxml', 'augment', 'choice', 'contact',"
-                + " 'container', 'description', 'extension', 'deviation', 'feature', 'grouping', 'identity', 'import',"
-                + " 'include', 'leaf', 'leaf-list', 'list', 'notification', 'organization', 'reference',"
-                + " 'revision', 'rpc', 'typedef', 'uses', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/ModuleSubStatementMandatory.yang");
-    }
 }
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java
index aa0cee2..29e4c63 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MaxElementsListenerTest.java
@@ -92,19 +92,6 @@
     }
 
     /**
-     * Checks whether exception is thrown when invalid max-elements keyword is
-     * given as input.
-     */
-    @Test
-    public void processMaxElementsInvalidStatement() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("extraneous input 'max-element' expecting {'config', 'description', 'if-feature',"
-                + " 'max-elements', 'min-elements', 'must', 'ordered-by', 'reference', 'status', 'type', 'units', "
-                + "'when', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/MaxElementsInvalidStatement.yang");
-    }
-
-    /**
      * Checks whether exception is thrown when max-elements statement without
      * statement end is given as input.
      */
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java
index c2f668b..e362eeb 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/MinElementsListenerTest.java
@@ -92,19 +92,6 @@
     }
 
     /**
-     * Checks whether exception is thrown when invalid min-elements keyword is
-     * given as input.
-     */
-    @Test
-    public void processMinElementsInvalidKeyword() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("extraneous input 'min-element' expecting {'config', 'description', 'if-feature',"
-                + " 'max-elements', 'min-elements', 'must', 'ordered-by', 'reference', 'status', 'type', 'units',"
-                + " 'when', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/MinElementsInvalidKeyword.yang");
-    }
-
-    /**
      * Checks whether exception is thrown when invalid min-elements value is
      * given as input.
      */
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/StatusListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/StatusListenerTest.java
index e6c840d..6d97bb8 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/StatusListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/StatusListenerTest.java
@@ -145,19 +145,6 @@
     }
 
     /**
-     * Checks status statement as sub-statement of module.
-     */
-    @Test
-    public void processModuleSubStatementStatus() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("mismatched input 'status' expecting {'anyxml', 'augment', 'choice', 'contact', "
-                + "'container', 'description', 'extension', 'deviation', 'feature', 'grouping', 'identity', 'import',"
-                + " 'include', 'leaf', 'leaf-list', 'list', 'notification', 'organization', 'reference', "
-                + "'revision', 'rpc', 'typedef', 'uses', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/ModuleSubStatementStatus.yang");
-    }
-
-    /**
      * Checks status statement as sub-statement of container.
      */
     @Test
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnionListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnionListenerTest.java
index 04b3796..1fe7218 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnionListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnionListenerTest.java
@@ -138,4 +138,12 @@
 
         YangNode node = manager.getDataModel("src/test/resources/UnionWithEmptyType.yang");
     }
+
+    /**
+     * Checks whether type union has atleast one type statement.
+     */
+    @Test (expected = ParserException.class)
+    public void processUnionWithoutChild() throws IOException, ParserException {
+        manager.getDataModel("src/test/resources/UnionWithoutChild.yang");
+    }
 }
diff --git a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java
index 6684df5..fe2bed1 100644
--- a/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java
+++ b/utils/yangutils/plugin/src/test/java/org/onosproject/yangutils/parser/impl/listeners/UnitsListenerTest.java
@@ -71,19 +71,6 @@
     }
 
     /**
-     * Checks invalid units statement as sub-statement of module.
-     */
-    @Test
-    public void processModuleSubStatementUnits() throws IOException, ParserException {
-        thrown.expect(ParserException.class);
-        thrown.expectMessage("mismatched input 'type' expecting {'anyxml', 'augment', 'choice', 'contact', "
-                + "'container', 'description', 'extension', 'deviation', 'feature', 'grouping', 'identity',"
-                + " 'import', 'include', 'leaf', 'leaf-list', 'list', 'notification', 'organization', "
-                + "'reference', 'revision', 'rpc', 'typedef', 'uses', '}'}");
-        YangNode node = manager.getDataModel("src/test/resources/ModuleSubStatementUnits.yang");
-    }
-
-    /**
      * Checks invalid units statement(without statement end).
      */
     @Test
diff --git a/utils/yangutils/plugin/src/test/resources/LeafInvalidStatement.yang b/utils/yangutils/plugin/src/test/resources/LeafInvalidStatement.yang
deleted file mode 100644
index 4d4f6f6..0000000
--- a/utils/yangutils/plugin/src/test/resources/LeafInvalidStatement.yang
+++ /dev/null
@@ -1,14 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    leafs invalid-interval {
-        type "uint16";
-        units "seconds";
-        description "Interval before a route is declared invalid";
-        config true;
-        mandatory true;
-        status current;
-        reference "RFC 6020";
-    }
-}
\ No newline at end of file
diff --git a/utils/yangutils/plugin/src/test/resources/MaxElementsInvalidStatement.yang b/utils/yangutils/plugin/src/test/resources/MaxElementsInvalidStatement.yang
deleted file mode 100644
index 67cb358..0000000
--- a/utils/yangutils/plugin/src/test/resources/MaxElementsInvalidStatement.yang
+++ /dev/null
@@ -1,14 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    leaf-list invalid-interval {
-        type "uint16";
-        units "seconds";
-        max-element 3;
-        description "Interval before a route is declared invalid;
-        config true;
-        status current;
-        reference "RFC 6020";
-    }
-}
diff --git a/utils/yangutils/plugin/src/test/resources/MinElementsInvalidKeyword.yang b/utils/yangutils/plugin/src/test/resources/MinElementsInvalidKeyword.yang
deleted file mode 100644
index e634509..0000000
--- a/utils/yangutils/plugin/src/test/resources/MinElementsInvalidKeyword.yang
+++ /dev/null
@@ -1,14 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    leaf-list invalid-interval {
-        type "uint16";
-        units "seconds";
-        min-element 3;
-        description "Interval before a route is declared invalid";
-        config true;
-        status current;
-        reference "RFC 6020";
-    }
-}
\ No newline at end of file
diff --git a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementConfig.yang b/utils/yangutils/plugin/src/test/resources/ModuleSubStatementConfig.yang
deleted file mode 100644
index 49deb3e..0000000
--- a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementConfig.yang
+++ /dev/null
@@ -1,6 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    config invalid;
-}
\ No newline at end of file
diff --git a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementMandatory.yang b/utils/yangutils/plugin/src/test/resources/ModuleSubStatementMandatory.yang
deleted file mode 100644
index 8f6e1a1..0000000
--- a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementMandatory.yang
+++ /dev/null
@@ -1,6 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    mandatory false;
-}
\ No newline at end of file
diff --git a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementStatus.yang b/utils/yangutils/plugin/src/test/resources/ModuleSubStatementStatus.yang
deleted file mode 100644
index 3739096..0000000
--- a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementStatus.yang
+++ /dev/null
@@ -1,6 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    status current;
-}
\ No newline at end of file
diff --git a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementUnits.yang b/utils/yangutils/plugin/src/test/resources/ModuleSubStatementUnits.yang
deleted file mode 100644
index d9381ec..0000000
--- a/utils/yangutils/plugin/src/test/resources/ModuleSubStatementUnits.yang
+++ /dev/null
@@ -1,7 +0,0 @@
-module Test {
-    yang-version 1;
-    namespace http://huawei.com;
-    prefix Ant;
-    type "uint16";
-    units "seconds";
-}
\ No newline at end of file
diff --git a/utils/yangutils/plugin/src/test/resources/UnionWithoutChild.yang b/utils/yangutils/plugin/src/test/resources/UnionWithoutChild.yang
new file mode 100644
index 0000000..14d3329
--- /dev/null
+++ b/utils/yangutils/plugin/src/test/resources/UnionWithoutChild.yang
@@ -0,0 +1,14 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        key "invalid-interval";
+        leaf invalid-interval {
+            type union {
+               type "union";
+            }
+        }
+    }
+}
+