diff --git a/.travis/unittest.sh b/.travis/unittest.sh
index 8e3071d05be0b8041dc04acf0d7c7ceb06298c44..c152a1bc57e156f4a1856d6dc9aa0d787d929bc9 100755
--- a/.travis/unittest.sh
+++ b/.travis/unittest.sh
@@ -1,5 +1,14 @@
 #!/bin/bash
 
+
+
+abort(){
+    echo "Run unittest failed" 1>&2
+    echo "Please check your code" 1>&2
+    exit 1
+}
+
+
 unittest(){
     cd $1 > /dev/null
     find . -path ./tools/venv -prune -false -o -name 'tests' -type d -print0 | \
@@ -8,17 +17,22 @@ unittest(){
     cd - > /dev/null
 }
 
-abort(){
-    echo "Run unittest failed" 1>&2
-    echo "Please check your code" 1>&2
-    exit 1
+coverage(){
+    cd $1 > /dev/null
+    find . -path ./tools/venv -prune -false -o -name 'tests' -type d -print0 | \
+        xargs -0 -I{} -n1 bash -c \
+        'python3 -m coverage run --branch {}'
+    python3 -m coverage report -m
+    python3 -m coverage html
+    cd - > /dev/null
 }
 
 trap 'abort' 0
 set -e
 
 source tools/venv/bin/activate
-pip3 install pytest
-unittest .
+#pip3 install pytest
+#unittest .
+coverage .
 
 trap : 0
diff --git a/deepspeech/exps/u2/model.py b/deepspeech/exps/u2/model.py
index 0a09eeda106db2bd2a76a4c63c5f1e551fcf7c7a..6221b93183e89cda7d6c515d48d9eb66e3fd0d12 100644
--- a/deepspeech/exps/u2/model.py
+++ b/deepspeech/exps/u2/model.py
@@ -74,7 +74,7 @@ class U2Trainer(Trainer):
     def __init__(self, config, args):
         super().__init__(config, args)
 
-    def train_batch(self, batch_data):
+    def train_batch(self, batch_data, msg):
         train_conf = self.config.training
         self.model.train()
 
@@ -93,12 +93,9 @@ class U2Trainer(Trainer):
             'train_att_loss': float(attention_loss),
             'train_ctc_loss': float(ctc_loss),
         }
-        msg = "Train: Rank: {}, ".format(dist.get_rank())
-        msg += "epoch: {}, ".format(self.epoch)
-        msg += "step: {}, ".format(self.iteration)
         msg += "time: {:>.3f}s, ".format(iteration_time)
-        msg += f"batch size: {self.config.data.batch_size}, "
-        msg += f"accum: {train_config.accum_grad}, "
+        msg += "batch size: {}, ".format(self.config.data.batch_size)
+        msg += "accum: {}, ".format(train_conf.accum_grad)
         msg += ', '.join('{}: {:>.6f}'.format(k, v)
                          for k, v in losses_np.items())
         if self.iteration % train_conf.log_interval == 0:
diff --git a/deepspeech/models/deepspeech2.py b/deepspeech/models/deepspeech2.py
index 727f64c02cd4922612a099194266a3f1f4c3f695..7cba2f2cb8c23d3d48fa71ffd2cd79041745b017 100644
--- a/deepspeech/models/deepspeech2.py
+++ b/deepspeech/models/deepspeech2.py
@@ -16,6 +16,7 @@ import logging
 from typing import Optional
 from yacs.config import CfgNode
 
+import paddle
 from paddle import nn
 
 from deepspeech.modules.conv import ConvStack
diff --git a/deepspeech/models/u2.py b/deepspeech/models/u2.py
index c875a5ab546d90c54482bd449fb16abe77e00236..95c13d4028273719c90d849a3506b3871aba521c 100644
--- a/deepspeech/models/u2.py
+++ b/deepspeech/models/u2.py
@@ -761,8 +761,10 @@ class U2Model(U2BaseModel):
         Returns:
             DeepSpeech2Model: The model built from pretrained result.
         """
-        config.input_dim = self.dataset.feature_size
-        config.output_dim = self.dataset.vocab_size
+        config.defrost()
+        config.input_dim = dataset.feature_size
+        config.output_dim = dataset.vocab_size
+        config.freeze()
         model = cls.from_config(config)
 
         if checkpoint_path:
diff --git a/deepspeech/training/trainer.py b/deepspeech/training/trainer.py
index b03508cb8e71e76b5990e5ba7a7070bdfff2a76f..982faa989dfc0956f709670aea9b5760c15ea698 100644
--- a/deepspeech/training/trainer.py
+++ b/deepspeech/training/trainer.py
@@ -181,13 +181,12 @@ class Trainer():
                     msg += "epoch: {}, ".format(self.epoch)
                     msg += "step: {}, ".format(self.iteration)
                     msg += "dataloader time: {:>.3f}s, ".format(dataload_time)
-                    self.logger.info(msg)
                     self.iteration += 1
-                    self.train_batch(batch)
+                    self.train_batch(batch, msg)
                     data_start_time = time.time()
             except Exception as e:
                 self.logger.error(e)
-                pass
+                raise e
 
             self.valid()
             self.save()
diff --git a/examples/tiny/s1/local/export.sh b/examples/tiny/s1/local/export.sh
new file mode 100644
index 0000000000000000000000000000000000000000..864ecb2d5bf754c1af1ea2c4787f7d24e66c83ef
--- /dev/null
+++ b/examples/tiny/s1/local/export.sh
@@ -0,0 +1,20 @@
+#! /usr/bin/env bash
+
+if [ $# != 2 ];then
+    echo "usage: export ckpt_path jit_model_path"
+    exit -1
+fi
+
+python3 -u ${BIN_DIR}/export.py \
+--config conf/conformer.yaml \
+--checkpoint_path ${1} \
+--export_path ${2} 
+
+
+if [ $? -ne 0 ]; then
+    echo "Failed in evaluation!"
+    exit 1
+fi
+
+
+exit 0
diff --git a/examples/tiny/s1/local/test.sh b/examples/tiny/s1/local/test.sh
new file mode 100644
index 0000000000000000000000000000000000000000..6dbb1c388986cbd60248ffe368369d3d3513e358
--- /dev/null
+++ b/examples/tiny/s1/local/test.sh
@@ -0,0 +1,22 @@
+#! /usr/bin/env bash
+
+# download language model
+bash local/download_lm_en.sh
+if [ $? -ne 0 ]; then
+    exit 1
+fi
+
+CUDA_VISIBLE_DEVICES=0 \
+python3 -u ${BIN_DIR}/test.py \
+--device 'gpu' \
+--nproc 1 \
+--config conf/conformer.yaml \
+--output ckpt
+
+if [ $? -ne 0 ]; then
+    echo "Failed in evaluation!"
+    exit 1
+fi
+
+
+exit 0
diff --git a/examples/tiny/s1/local/train.sh b/examples/tiny/s1/local/train.sh
index c2e62c613c94ef7f06f94cbd11126b9d6ba26d10..6511614a99bacba58b69fadf6482e39d6f206fba 100644
--- a/examples/tiny/s1/local/train.sh
+++ b/examples/tiny/s1/local/train.sh
@@ -1,7 +1,5 @@
 #! /usr/bin/env bash
 
-export FLAGS_sync_nccl_allreduce=0
-
 CUDA_VISIBLE_DEVICES=0 \
 python3 -u ${BIN_DIR}/train.py \
 --device 'gpu' \
diff --git a/requirements.txt b/requirements.txt
index bfc45d0b8413914c143a603795c4f128299cdd97..40b4cef38cf7e75acc33e7726827839203ca9d5f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
+coverage
 pre-commit
 python_speech_features
 resampy==0.2.2