fix unit test bug when only one gpu

paddle/trainer/tests/test_Trainer.cpp

@@ -62,7 +62,11 @@ TEST(checkGradient, multiGpu) {
   }
 }
 
-TEST(checkGradient, parallel) { checkGradientTest(configFile4, true, true); }
+TEST(checkGradient, parallel) {
+  if (hl_get_device_count() >= 2) {
+    checkGradientTest(configFile4, true, true);
+  }
+}
 
 TEST(checkGradient, multiParallel) {
   FLAGS_allow_only_one_model_on_one_gpu = false;
@@ -90,7 +94,7 @@ TEST(checkGradient, multi) {
 TEST(checkGradient, hsigmoid) { checkGradientTest(configFile2, false, false); }
 
 TEST(checkGradient, chunk) {
-  EXPECT_EQ(0, system("python2 trainer/tests/gen_proto_data.py"));
+  EXPECT_EQ(0, system("python trainer/tests/gen_proto_data.py"));
   checkGradientTest(configFile3, false, false);
 #ifndef PADDLE_ONLY_CPU
   checkGradientTest(configFile3, true, true);

paddle/trainer/tests/test_TrainerOnePass.cpp

@@ -82,7 +82,11 @@ TEST(trainerOnePass, gpu2) { trainerOnePassTest(configFile1, true, false, 2); }
 
 TEST(trainerOnePass, gpu4) { trainerOnePassTest(configFile1, true, false, 4); }
 
-TEST(trainerOnePass, parallel) { trainerOnePassTest(configFile2, true, true); }
+TEST(trainerOnePass, parallel) {
+  if (hl_get_device_count() >= 2) {
+    trainerOnePassTest(configFile2, true, true);
+  }
+}
 #endif
 
 // 2. test average_window.