1 files changed, 78 insertions, 8 deletions

diff --git a/spec/README.md b/spec/README.md
index 23fc7507c3..6a88c06e09 100644
--- a/spec/README.md
+++ b/spec/README.md
@@ -1,14 +1,23 @@
 # spec/bundler
 
-spec/bundler is rspec examples for bundler library(lib/bundler.rb, lib/bundler/*).
+spec/bundler is rspec examples for bundler library (`lib/bundler.rb`, `lib/bundler/*`).
 
 ## Running spec/bundler
 
 To run rspec for bundler:
+
 ```bash
 make test-bundler
 ```
 
+or run rspec with parallel execution:
+
+```bash
+make test-bundler-parallel
+```
+
+If you specify `BUNDLER_SPECS=foo/bar_spec.rb` then only `spec/bundler/foo/bar_spec.rb` will be run.
+
 # spec/ruby
 
 ruby/spec (https://github.com/ruby/spec/) is
@@ -30,31 +39,80 @@ In other words: If adding a spec might reveal a bug in
 another implementation, then it is worth adding it.
 Currently, the only module which is MRI-specific is `RubyVM`.
 
+## Changing behavior and versions guards
+
+Version guards (`ruby_version_is`) must be added for new features or features
+which change behavior or are removed. This is necessary for other Ruby implementations
+to still be able to run the specs and contribute new specs.
+
+For example, change:
+
+```ruby
+describe "Some spec" do
+  it "some example" do
+    # Old behavior for Ruby < 2.7
+  end
+end
+```
+
+to:
+
+```ruby
+describe "Some spec" do
+  ruby_version_is ""..."2.7" do
+    it "some example" do
+      # Old behavior for Ruby < 2.7
+    end
+  end
+
+  ruby_version_is "2.7" do
+    it "some example" do
+      # New behavior for Ruby >= 2.7
+    end
+  end
+end
+```
+
+See `spec/ruby/CONTRIBUTING.md` for more documentation about guards.
+
+To verify specs are compatible with older Ruby versions:
+
+```bash
+cd spec/ruby
+$RUBY_MANAGER use 2.4.9
+../mspec/bin/mspec -j
+```
+
 ## Running ruby/spec
 
 To run all specs:
+
 ```bash
 make test-spec
 ```
 
-Extra arguments can be added via `MSPECOPT`.
+Extra arguments can be added via `SPECOPTS`.
 For instance, to show the help:
+
 ```bash
-make test-spec MSPECOPT=-h
+make test-spec SPECOPTS=-h
 ```
 
 You can also run the specs in parallel, which is currently experimental.
 It takes around 10s instead of 60s on a quad-core laptop.
+
 ```bash
-make test-spec MSPECOPT=-j
+make test-spec SPECOPTS=-j
 ```
 
 To run a specific test, add its path to the command:
+
 ```bash
-make test-spec MSPECOPT=spec/ruby/language/for_spec.rb
+make test-spec SPECOPTS=spec/ruby/language/for_spec.rb
 ```
 
 If ruby trunk is your current `ruby` in `$PATH`, you can also run `mspec` directly:
+
 ```bash
 # change ruby to trunk
 ruby -v # => trunk
@@ -63,8 +121,8 @@ spec/mspec/bin/mspec spec/ruby/language/for_spec.rb
 
 ## ruby/spec and test/
 
-The main difference between a "spec" under spec/ruby and
-a test under test/ is that specs are documenting what they test.
+The main difference between a "spec" under `spec/ruby/` and
+a test under `test/` is that specs are documenting what they test.
 This is extremely valuable when reading these tests, as it
 helps to quickly understand what specific behavior is tested,
 and how a method should behave. Basic English is fine for spec descriptions.
@@ -87,4 +145,16 @@ describe "The for expression" do
 end
 ```
 
-For more details, see spec/ruby/CONTRIBUTING.md.
+For more details, see `spec/ruby/CONTRIBUTING.md`.
+
+# spec/syntax_suggest
+
+## Running spec/syntax_suggest
+
+To run rspec for syntax_suggest:
+
+```bash
+make test-syntax-suggest
+```
+
+If you specify `SYNTAX_SUGGEST_SPECS=foo/bar_spec.rb` then only `spec/syntax_suggest/foo/bar_spec.rb` will be run.