disable foreign keys for sqlite before dropping all tables

lib/dialects/sqlite/query-interface.js

@@ -118,5 +118,60 @@ var QueryInterface = module.exports = {
           queryAndEmit.call(this, queries.splice(queries.length - 1)[0], methodName, {}, emitter)
         }
       }.bind(this))
+  },
+
+  dropAllTables: function() {
+    var self = this
+
+   return new Utils.CustomEventEmitter(function(dropAllTablesEmitter) {
+      var events  = []
+        , chainer = new Utils.QueryChainer()
+        , onError = function(err) {
+            self.emit('dropAllTables', err)
+            dropAllTablesEmitter.emit('error', err)
+          }
+
+      self
+        .showAllTables()
+        .error(onError)
+        .success(function(tableNames) {
+          self
+            .sequelize
+            .query('PRAGMA foreign_keys;')
+            .proxy(dropAllTablesEmitter, { events: ['sql'] })
+            .error(onError)
+            .success(function(result) {
+              var foreignKeysAreEnabled = result.foreign_keys === 1
+
+              if (foreignKeysAreEnabled) {
+                var queries = []
+
+                queries.push('PRAGMA foreign_keys = OFF')
+
+                tableNames.forEach(function(tableName) {
+                  queries.push(self.QueryGenerator.dropTableQuery(tableName).replace(';', ''))
+                })
+
+                queries.push('PRAGMA foreign_keys = ON')
+
+                QueryInterface.execMultiQuery.call(self, queries, 'dropAllTables', dropAllTablesEmitter, self.queryAndEmit)
+              } else {
+                // add the table removal query to the chainer
+                tableNames.forEach(function(tableName) {
+                  chainer.add(self, 'dropTable', [ tableName, { cascade: true } ])
+                })
+
+                chainer
+                  .runSerially()
+                  .proxy(dropAllTablesEmitter, { events: ['sql'] })
+                  .error(onError)
+                  .success(function() {
+                    self.emit('dropAllTables', null)
+                    dropAllTablesEmitter.emit('success', null)
+                  })
+              }
+            })
+        })
+    }).run()
   }
 }