fix test for theano

test/test_custom_loss.py

@@ -13,11 +13,19 @@ from mhcflurry.custom_loss import CUSTOM_LOSSES
 
 
 def evaluate_loss(loss, y_true, y_pred):
-    session = K.get_session()
-    y_true_var = K.constant(y_true, name="y_true")
-    y_pred_var = K.constant(y_pred, name="y_pred")
-    result = loss(y_true_var, y_pred_var)
-    return result.eval(session=session)
+    if K.backend() == "tensorflow":
+        session = K.get_session()
+        y_true_var = K.constant(y_true, name="y_true")
+        y_pred_var = K.constant(y_pred, name="y_pred")
+        result = loss(y_true_var, y_pred_var)
+        return result.eval(session=session)
+    elif K.backend() == "theano":
+        y_true_var = K.constant(y_true, name="y_true")
+        y_pred_var = K.constant(y_pred, name="y_pred")
+        result = loss(y_true_var, y_pred_var)
+        return result.eval()
+    else:
+        raise ValueError("Unsupported backend: %s" % K.backend())
 
 
 def test_mse_with_inequalities():