diff --git a/test/listShards.js b/test/listShards.js
index e4475b5..4da2eaf 100644
--- a/test/listShards.js
+++ b/test/listShards.js
@@ -6,7 +6,8 @@ var target = 'ListShards',
     opts = helpers.opts.bind(null, target),
     assertType = helpers.assertType.bind(null, target),
     assertValidation = helpers.assertValidation.bind(null, target),
-    assertNotFound = helpers.assertNotFound.bind(null, target)
+    assertNotFound = helpers.assertNotFound.bind(null, target),
+    assertInvalidArgument = helpers.assertInvalidArgument.bind(null, target)
 
 describe('listShards', function() {
 
@@ -24,19 +25,24 @@ describe('listShards', function() {
       assertType('ExclusiveStartShardId', 'String', done)
     })
 
+    it('should return SerializationException when NextToken is not a String', function(done) {
+      assertType('NextToken', 'String', done)
+    })
+
+    it('should return SerializationException when StreamCreationTimestamp is not a Timestamp', function(done) {
+      assertType('StreamCreationTimestamp', 'Timestamp', done)
+    })
+
   })
 
   describe('validations', function() {
 
-    it('should return ValidationException for no StreamName', function(done) {
-      assertValidation({}, [
-        'Value null at \'streamName\' failed to satisfy constraint: ' +
-        'Member must not be null',
-      ], done)
+    it('should return InvalidArgumentException for no StreamName or NextToken', function(done) {
+      assertInvalidArgument({}, 'Either NextToken or StreamName should be provided.', done)
     })
 
     it('should return ValidationException for empty StreamName', function(done) {
-      assertValidation({StreamName: '', MaxResults: 0, ExclusiveStartShardId: ''}, [
+      assertValidation({StreamName: '', NextToken: '', MaxResults: 0, ExclusiveStartShardId: ''}, [
         'Value \'0\' at \'maxResults\' failed to satisfy constraint: ' +
         'Member must have value greater than or equal to 1',
         'Value \'\' at \'exclusiveStartShardId\' failed to satisfy constraint: ' +
@@ -47,6 +53,8 @@ describe('listShards', function() {
         'Member must satisfy regular expression pattern: [a-zA-Z0-9_.-]+',
         'Value \'\' at \'streamName\' failed to satisfy constraint: ' +
         'Member must have length greater than or equal to 1',
+        'Value \'\' at \'nextToken\' failed to satisfy constraint: ' +
+        'Member must have length greater than or equal to 1',
       ], done)
     })
 
@@ -62,6 +70,12 @@ describe('listShards', function() {
       ], done)
     })
 
+    it('should return InvalidArgumentException if both StreamName and NextToken', function(done) {
+      var name = randomName()
+      assertInvalidArgument({StreamName: name, NextToken: name},
+        'NextToken and StreamName cannot be provided together.', done)
+    })
+
     it('should return ResourceNotFoundException if stream does not exist', function(done) {
       var name = randomName()
       assertNotFound({StreamName: name}, 'Stream ' + name + ' under account ' +
@@ -72,7 +86,7 @@ describe('listShards', function() {
 
   describe('functionality', function() {
 
-    it('should return stream description', function(done) {
+    it('should return stream shards', function(done) {
       request(opts({StreamName: helpers.testStream}), function(err, res) {
         if (err) return done(err)
         res.statusCode.should.equal(200)