Add empty string check for collection name passed

lib/utils.js

@@ -53,6 +53,12 @@ exports.toCollectionName = function(name, pluralize) {
     return name;
   }
   if (typeof pluralize === 'function') {
+    if (typeof name !== 'string') {
+      throw new TypeError('Collection name must be a string');
+    }
+    if (name.length === 0) {
+      throw new TypeError('Collection name cannot be empty');
+    }
     return pluralize(name);
   }
   return name;

test/utils.test.js

@@ -324,4 +324,31 @@ describe('utils', function() {
       assert.deepEqual(pojoError.metadata, { hello: 'world' });
     });
   });
+
+  describe('toCollectionName', function() {
+    it('returns the same name for system.profile', function() {
+      assert.equal(utils.toCollectionName('system.profile'), 'system.profile');
+    });
+
+    it('returns the same name for system.indexes', function() {
+      assert.equal(utils.toCollectionName('system.indexes'), 'system.indexes');
+    });
+
+    it('throws an error when name is not a string', function() {
+      assert.throws(() => {
+        utils.toCollectionName(123, () => {});
+      }, /Collection name must be a string/);
+    });
+
+    it('throws an error when name is an empty string', function() {
+      assert.throws(() => {
+        utils.toCollectionName('', () => {});
+      }, /Collection name cannot be empty/);
+    });
+
+    it('uses the pluralize function when provided', function() {
+      const pluralize = (name) => name + 's';
+      assert.equal(utils.toCollectionName('test', pluralize), 'tests');
+    });
+  });
 });