Have AppVeyor run the tests.

appveyor.yml

@@ -66,13 +66,8 @@ build_script:
       -DCMAKE_PREFIX_PATH=%INSTALL_PREFIX_VS2015%
   - cmake --build build-vs2015-samples --config %BUILD_TYPE%
 
-# TODO(soon): Fix tests on Windows.
-#
-# Tests are not currently run, because until the tests start passing normally, it's more useful for
-# us to only be notified of build errors. When they start passing, uncomment the code below.
-#
-#test_script:
-#  - timeout /t 2
-#  # Sleep a little to prevent interleaving test output with build output.
-#  - cd build-msvc\src
-#  - ctest -V -C %BUILD_TYPE%
+test_script:
+  - timeout /t 2
+  # Sleep a little to prevent interleaving test output with build output.
+  - cd build-vs2015\src
+  - ctest -V -C %BUILD_TYPE%