Add instructions to run tests locally (#1868)

docs/contribute/pull_request.rst

@@ -24,3 +24,50 @@ This is a quick guide to submit a pull request, please also refer to the detaile
   - The detailed guidelines and summarizes useful lessons.
 
 - The patch can be merged after the reviewers approve the pull request.
+
+Testing
+-------
+Even though we have hooks to run unit tests automatically for each pull request, It's always recommended to run unit tests
+locally beforehand to reduce reviewers' burden and speedup review process.
+
+C++
+^^^
+.. code:: bash
+
+  # assume you are in tvm source root
+  TVM_ROOT=`pwd`
+
+  # you need to install google test first, gtest will be installed to $TVM_ROOT/lib
+  CACHE_PREFIX=. make -f 3rdparty/dmlc-core/scripts/packages.mk gtest
+
+  mkdir build
+  cd build
+  GTEST_LIB=$TVM_ROOT/lib cmake ..
+  make cpptest -j
+  for test in *_test; do
+    ./$test || exit -1
+  done
+
+Python
+^^^^^^
+If you want to run all tests:
+
+.. code:: bash
+
+  # build tvm
+  make
+
+  ./tests/scripts/task_python_unittest.sh
+
+If you want to run a single test:
+
+.. code:: bash
+
+  # build tvm
+  make
+
+  # let python know where to find tvm related libraries
+  export PYTHONPATH=python:topi/python
+  rm -rf python/tvm/*.pyc python/tvm/*/*.pyc python/tvm/*/*/*.pyc
+
+  TVM_FFI=ctypes python -m nose -v tests/python/unittest/test_pass_storage_rewrite.py
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