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+# Testing Ruby
+
+## Test suites
+
+There are several test suites in the Ruby codebase:
+
+We can run any of the make scripts [in parallel](building_ruby.md#label-Running+make+scripts+in+parallel) to speed them up.
+
+1. [bootstraptest/](https://github.com/ruby/ruby/tree/master/bootstraptest)
+
+    This is a small test suite that runs on Miniruby (see [building Ruby](building_ruby.md#label-Miniruby+vs+Ruby)). We can run it with:
+
+    ```
+    make btest
+    ```
+
+    To run it with logs, we can use:
+
+    ```
+    make btest OPTS=-v
+    ```
+
+    To run individual bootstrap tests, we can either specify a list of filenames or use the `--sets` flag in the variable `BTESTS`:
+
+    ```
+    make btest BTESTS="bootstraptest/test_fork.rb bootstraptest/tes_gc.rb"
+    make btest BTESTS="--sets=fork,gc"
+    ```
+
+    If we want to run the bootstrap test suite on Ruby (not Miniruby), we can use:
+
+    ```
+    make test
+    ```
+
+    To run it with logs, we can use:
+
+    ```
+    make test OPTS=-v
+    ```
+
+    To run a file or directory with GNU make, we can use:
+
+    ```
+    make test/ruby/test_foo.rb
+    make test/ruby/test_foo.rb TESTOPTS="-n /test_bar/"
+    ```
+
+2. [test/](https://github.com/ruby/ruby/tree/master/test)
+
+    This is a more comprehensive test suite that runs on Ruby. We can run it with:
+
+    ```
+    make test-all
+    ```
+
+    We can run a specific test directory in this suite using the `TESTS` option, for example:
+
+    ```
+    make test-all TESTS=test/rubygems
+    ```
+
+    We can run a specific test file in this suite by also using the `TESTS` option, for example:
+
+    ```
+    make test-all TESTS=test/ruby/test_array.rb
+    ```
+
+    We can run a specific test in this suite using the `TESTS` option, specifying
+    first the file name, and then the test name, prefixed with `--name`. For example:
+
+    ```
+    make test-all TESTS="../test/ruby/test_alias.rb --name=TestAlias#test_alias_with_zsuper_method"
+    ```
+
+    To run these specs with logs, we can use:
+
+    ```
+    make test-all TESTS=-v
+    ```
+
+    We can display the help of the `TESTS` option:
+
+    ```
+    make test-all TESTS=--help
+    ```
+
+    If we would like to run the `test/`, `bootstraptest/` and `spec/` test suites (the `spec/` is explained in a later section), we can run
+
+    ```
+    make check
+    ```
+
+3. [spec/ruby](https://github.com/ruby/ruby/tree/master/spec/ruby)
+
+    This is a test suite that exists in [the Ruby spec repository](https://github.com/ruby/spec) and is mirrored into the `spec/ruby` directory in the Ruby repository. It tests the behavior of the Ruby programming language. We can run this using:
+
+    ```
+    make test-spec
+    ```
+
+    To run a specific directory, we can use `SPECOPTS` to specify the directory:
+
+    ```
+    make test-spec SPECOPTS=spec/ruby/core/array
+    ```
+
+    To run a specific file, we can also use `SPECOPTS` to specify the file:
+
+    ```
+    make test-spec SPECOPTS=spec/ruby/core/array/any_spec.rb
+    ```
+
+    To run a specific test, we can use the `--example` flag to match against the test name:
+
+    ```
+    make test-spec SPECOPTS="../spec/ruby/core/array/any_spec.rb --example='is false if the array is empty'"
+    ```
+
+    To run these specs with logs, we can use:
+
+    ```
+    make test-spec SPECOPTS=-Vfs
+    ```
+
+    To run a ruby-spec file or directory with GNU make, we can use
+
+    ```
+    make spec/ruby/core/foo/bar_spec.rb
+    ```
+
+4. [spec/bundler](https://github.com/ruby/ruby/tree/master/spec/bundler)
+
+    The bundler test suite exists in [the RubyGems repository](https://github.com/rubygems/rubygems/tree/master/bundler/spec) and is mirrored into the `spec/bundler` directory in the Ruby repository. We can run this using:
+
+    ```
+    make test-bundler
+    ```
+
+    To run a specific bundler spec file, we can use `BUNDLER_SPECS` as follows:
+
+    ```
+    make test-bundler BUNDLER_SPECS=commands/exec_spec.rb
+    ```
+
+## Troubleshooting
+
+### Running test suites on s390x CPU Architecture
+
+If we see failing tests related to the zlib library on s390x CPU architecture, we can run the test suites with `DFLTCC=0` to pass:
+
+```
+DFLTCC=0 make check
+```
+
+The failures can happen with the zlib library applying the patch [madler/zlib#410](https://github.com/madler/zlib/pull/410) to enable the deflate algorithm producing a different compressed byte stream. We manage this issue at [[ruby-core:114942][Bug #19909]](https://bugs.ruby-lang.org/issues/19909).