[WIP] Add testing guide (DO NOT MERGE)

content/docs/community/testing/_index.md

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+title = "Testing Guide"
+weight = 10
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+gVisor has an extensive test suite that covers unit tests for internal data
+structions, as well as syscall tests for testing Linux compatibility.
+
+# Running tests
+
+Tests are built and run using [Bazel](https://bazel.build/) and are specified
+in `BUILD` files in various directories thoughout the source tree. Bazel uses
+the directory structure and `BUILD` files to define a "package" (See the
+[Bazel documentation](https://docs.bazel.build/versions/master/build-ref.html#packages_targets)).
+The entire repository is referred to as a Bazel "workspace".
+
+The entire test suite can be run with the following command. This command is
+using the double slash (//) operator to specify the root of the workspace and
+the elipsis (...) operator as a wildcard to specify that all tests under the
+root workspace should be run. This will include both unit tests and syscall
+tests.
+
+```
+bazel test //...
+```
+
+Running specific test suites or targets is done using variations of the
+`bazel test` command.
+
+# Running unit tests
+
+Running unit tests is fairly straightforward in the Bazel style. Running all
+unit tests is a matter of specifying all of the Go base packages.
+
+```
+bazel test //runsc/... //pkg/... //tools/...
+```
+
+You can also specify individual targets to run tests.
+
+```
+bazel test //runsc/boot:boot_test
+```
+
+# Running syscall tests
+
+Syscall tests are used to verify the compatibility between gVisor and Linux
+behavior. They are found under the `test/syscalls` directory in the project
+root.  Limiting test execution to the syscall tests can be done by specifying
+them as a target.
+
+```
+bazel test //test/syscalls/...
+```
+
+Individual syscall test targets can be found in the Bazel `BUILD` files under
+`test/syscalls`. For instance `test/syscalls/linux/BUILD`.
+
+The targets specified in the `BUILD` file will not include any actual tests. For example,
+running `bazel test test/syscalls/linux:exec_test` will result in the
+following:
+
+```
+$ bazel test //test/syscalls:exec_test
+...
+ERROR: No test targets were found, yet testing was requested
+...
+```
+
+The actual test targets are generated for Linux and for each gVisor platform
+(see [Platforms](/docs/user_guide/platforms/)) and are of the form `<BUILD
+target>_native` for Linux and `<BUILD target>_runsc_<platform>` for gVisor
+tests, and fall under the `test/syscalls` package. For example, to run the
+`exec_test` on Linux you would run the following:
+
+```
+$ bazel test //test/syscalls:exec_test_native
+```
+
+To run the gVisor version of the test on the ptrace platform, you would run the
+following:
+
+```
+$ bazel test //test/syscalls:exec_test_runsc_ptrace
+```