add doc update (#17223)

Signed-off-by: fishbell <bell.song@intel.com>

src/plugins/auto/docs/tests.md

@@ -1,9 +1,52 @@
 # AUTO Plugin tests
 
-## AUTO plugin testing places
+## AUTO plugin Unit Tests
 
-TBD-100527
+Auto unit test is a set of unit tests using gmock, each of which is for testing selection logic, device list parser, meta device filter and all other internal functions of Auto plugin.
 
 ## How to run tests
 
-TBD-100527
+### Build unit test
+
+1. Turn on `ENABLE_TESTS` in cmake option:
+
+   ```bash
+   cmake -DCMAKE_BUILD_TYPE=Release \
+       -DENABLE_TESTS=ON \
+   ```
+
+2. Build
+
+   ```bash
+   make ieMultiPluginUnitTests
+   ```
+
+3. You can find `ieMultiPluginUnitTests` in *bin* directory after build
+
+### Run unit test
+
+You can run _`ieMultiPluginUnitTests`_ in *bin* directory which is the output of OpenVINO build
+
+If you want to run a specific unit test, you can use `gtest_filter` option as follows:
+
+```
+./ieMultiPluginUnitTests --gtest_filter='*filter_name*'
+```
+
+Then, you can get the result similar to:
+
+```bash
+openvino/bin/intel64/Release$ ./ieMultiPluginUnitTests --gtest_filter=*AutoReleaseHelperTest*cpuLoadFailure_accelerateorLoadFailure*
+Running main() from /home/openvino/thirdparty/gtest/gtest/googletest/src/gtest_main.cc
+Note: Google Test filter = *AutoReleaseHelperTest*cpuLoadFailure_accelerateorLoadFailure*
+[==========] Running 1 test from 1 test suite.
+[----------] Global test environment set-up.
+[----------] 1 test from smoke_Auto_BehaviorTests/AutoReleaseHelperTest
+[ RUN      ] smoke_Auto_BehaviorTests/AutoReleaseHelperTest.releaseResource/cpuLoadFailure_accelerateorLoadFailure
+[       OK ] smoke_Auto_BehaviorTests/AutoReleaseHelperTest.releaseResource/cpuLoadFailure_accelerateorLoadFailure (732 ms)
+[----------] 1 test from smoke_Auto_BehaviorTests/AutoReleaseHelperTest (732 ms total)
+
+[----------] Global test environment tear-down
+[==========] 1 test from 1 test suite ran. (732 ms total)
+[  PASSED  ] 1 test.
+```