discoverSchemas returns an error when modelName is not found,

discoverSchema forwards that error and does not hang when no columns,
no errors are returned

lib/datasource.js

@@ -1225,7 +1225,7 @@ DataSource.prototype.discoverSchema = function (modelName, options, cb) {
   cb = cb || utils.createPromiseCallback();
 
   this.discoverSchemas(modelName, options, function (err, schemas) {
-    if (err) {
+    if (err || !schemas) {
       cb && cb(err, schemas);
       return;
     }
@@ -1305,7 +1305,7 @@ DataSource.prototype.discoverSchemas = function (modelName, options, cb) {
 
     var columns = results[0];
     if (!columns || columns.length === 0) {
-      cb();
+      cb(new Error('Table \''+modelName+'\' does not exist.'));
       return cb.promise;
     }
 

test/discovery.test.js

@@ -602,3 +602,27 @@ describe('discoverExportedForeignKeys', function(){
       });
   });
 });
+
+describe('Default memory connector', function() {
+  var ds, nonExistantError = 'Table \'NONEXISTENT\' does not exist.';
+
+  before(function() {
+    ds = new DataSource({connector: 'memory'});
+  });
+
+  it('discoverSchema should return an error when table does not exist', function(done) {
+    ds.discoverSchema('NONEXISTENT', {}, function(err, schemas) {
+      should.exist(err);
+      err.message.should.eql(nonExistantError);
+      done();
+    });
+  });
+
+  it('discoverSchemas should return an error when table does not exist', function(done) {
+    ds.discoverSchemas('NONEXISTENT', {}, function(err, schemas) {
+      should.exist(err);
+      err.message.should.eql(nonExistantError);
+      done();
+    });
+  });
+});