Tests for coherence of hooks done

lib/persistence.js

@@ -21,6 +21,8 @@ var storage = require('./storage')
  *                                            Node Webkit stores application data such as cookies and local storage (the best place to store data in my opinion)
  */
 function Persistence (options) {
+  var i, j, randomString;
+  
   this.db = options.db;
   this.inMemoryOnly = this.db.inMemoryOnly;
   this.filename = this.db.filename;
@@ -36,13 +38,21 @@ function Persistence (options) {
 
   // After serialization and before deserialization hooks with some basic sanity checks
   if (options.afterSerialization && !options.beforeDeserialization) {
-    throw "Serialization hook defined but deserialization hook undefined, cautiously refusing to start NeDB";
+    throw "Serialization hook defined but deserialization hook undefined, cautiously refusing to start NeDB to prevent dataloss";
   }
   if (!options.afterSerialization && options.beforeDeserialization) {
-    throw "Serialization hook undefined but deserialization hook defined, cautiously refusing to start NeDB";
+    throw "Serialization hook undefined but deserialization hook defined, cautiously refusing to start NeDB to prevent dataloss";
   }
   this.afterSerialization = options.afterSerialization || function (s) { return s; };
   this.beforeDeserialization = options.beforeDeserialization || function (s) { return s; };
+  for (i = 1; i < 30; i += 1) {
+    for (j = 0; j < 10; j += 1) {
+      randomString = customUtils.uid(i);
+      if (this.beforeDeserialization(this.afterSerialization(randomString)) !== randomString) {
+        throw "beforeDeserialization is not the reverse of afterSerialization, cautiously refusing to start NeDB to prevent dataloss";
+      }
+    }
+  }
   
   // For NW apps, store data in the same directory where NW stores application data
   if (this.filename && options.nodeWebkitAppName) {

test/persistence.test.js

@@ -275,20 +275,48 @@ describe('Persistence', function () {
     it("Declaring only one hook will throw an exception to prevent data loss", function (done) {
       var hookTestFilename = 'workspace/hookTest.db'
       Persistence.ensureFileDoesntExist(hookTestFilename, function () {
+        fs.writeFileSync(hookTestFilename, "Some content", "utf8");
+      
         (function () {
           new Datastore({ filename: hookTestFilename, autoload: true
                         , afterSerialization: as
                         });
         }).should.throw();
         
+        // Data file left untouched
+        fs.readFileSync(hookTestFilename, "utf8").should.equal("Some content");
+        
         (function () {
           new Datastore({ filename: hookTestFilename, autoload: true
                         , beforeDeserialization: bd
                         });
         }).should.throw();
 
+        // Data file left untouched
+        fs.readFileSync(hookTestFilename, "utf8").should.equal("Some content");
+
+        done();
+      });
+    });
+    
+    it("Declaring two hooks that are not reverse of one another will cause an exception to prevent data loss", function (done) {
+      var hookTestFilename = 'workspace/hookTest.db'
+      Persistence.ensureFileDoesntExist(hookTestFilename, function () {
+        fs.writeFileSync(hookTestFilename, "Some content", "utf8");
+      
+        (function () {
+          new Datastore({ filename: hookTestFilename, autoload: true
+                        , afterSerialization: as
+                        , beforeDeserialization: function (s) { return s; }
+                        });
+        }).should.throw();
+
+        // Data file left untouched
+        fs.readFileSync(hookTestFilename, "utf8").should.equal("Some content");
+
         done();
       });
+    
     });
   
     it("A serialization hook can be used to transform data before writing new state to disk", function (done) {