diff --git a/lib/indexes.js b/lib/indexes.js
index 8271dbf..32701b6 100644
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -21,9 +21,9 @@ function Index (options) {
   this.fieldName = options.fieldName;
   this.datastore = options.datastore;
   this.unique = options.unique || false;
-  this.sparse = options.unique || false;
+  this.sparse = options.sparse || false;
 
-  if (this.sparse) { this.unindexedDocs = []; }
+  if (this.sparse) { this.nonindexedDocs = []; }
 
   this.tree = new BinarySearchTree({ unique: this.unique, compareKeys: model.compareThings, checkValueEquality: checkValueEquality });
 }
@@ -37,7 +37,7 @@ Index.prototype.insert = function (doc) {
 
   // We don't index documents that don't contain the field if the index is sparse
   if (key === undefined && this.sparse) {
-    this.unindexedDocs.push(doc);
+    this.nonindexedDocs.push(doc);
     return;
   }
 
diff --git a/test/indexes.test.js b/test/indexes.test.js
new file mode 100644
index 0000000..1680000
--- /dev/null
+++ b/test/indexes.test.js
@@ -0,0 +1,74 @@
+var Index = require('../lib/indexes')
+  , customUtils = require('../lib/customUtils')
+  , should = require('chai').should()
+  , assert = require('chai').assert
+  , _ = require('underscore')
+  , async = require('async')
+  , model = require('../lib/model')
+  ;
+
+describe('Indexing', function () {
+
+  describe('Insertion', function () {
+
+    it('Can insert pointers to documents in the index correctly when they have the field', function () {
+      var idx = new Index({ fieldName: 'tf' })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 8, tf: 'world' }
+        , doc3 = { a: 2, tf: 'bloup' }
+        ;
+
+      idx.insert(doc1);
+      idx.insert(doc2);
+      idx.insert(doc3);
+
+      // The underlying BST now has 3 nodes which contain the docs where it's expected
+      idx.tree.getNumberOfKeys().should.equal(3);
+      assert.deepEqual(idx.tree.search('hello'), [{ a: 5, tf: 'hello' }]);
+      assert.deepEqual(idx.tree.search('world'), [{ a: 8, tf: 'world' }]);
+      assert.deepEqual(idx.tree.search('bloup'), [{ a: 2, tf: 'bloup' }]);
+
+      // The nodes contain pointers to the actual documents
+      idx.tree.search('world')[0].should.equal(doc2);
+      idx.tree.search('bloup')[0].a = 42;
+      doc3.a.should.equal(42);
+    });
+
+    it('Inserting twice for the same fieldName in a unique index will result in an error thrown', function () {
+      var idx = new Index({ fieldName: 'tf', unique: true })
+        , doc1 = { a: 5, tf: 'hello' }
+        ;
+
+      idx.insert(doc1);
+      idx.tree.getNumberOfKeys().should.equal(1);
+      (function () { idx.insert(doc1); }).should.throw();
+    });
+
+    it('Inserting twice for a fieldName the docs dont have with a unique index results in an error thrown', function () {
+      var idx = new Index({ fieldName: 'nope', unique: true })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 5, tf: 'world' }
+        ;
+
+      idx.insert(doc1);
+      idx.tree.getNumberOfKeys().should.equal(1);
+      (function () { idx.insert(doc2); }).should.throw();
+    });
+
+    it('Inserting twice for a fieldName the docs dont have with a unique and sparse index will not throw, since the docs will be non indexed', function () {
+      var idx = new Index({ fieldName: 'nope', unique: true, sparse: true })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 5, tf: 'world' }
+        ;
+
+      idx.insert(doc1);
+      idx.insert(doc2);
+      idx.tree.getNumberOfKeys().should.equal(0);   // Docs are not indexed
+      assert.deepEqual(idx.nonindexedDocs, [doc1, doc2]);   // Pointers are stored in the non indexed documents
+      idx.nonindexedDocs[1].a = 12;
+      doc2.a.should.equal(12);
+    });
+
+  });   // ==== End of 'Insertion' ==== //
+
+});