fix: only group specs if the context or describe call has a block

[nathanscottdaniels]

The problem

If you have a spec with a let variable named one of the "reserved" words such as context or describe this gem interprets any usage of those variables as test group. This breaks the VS Code integration since these aren't actually test groups and tests don't actually exist within them.

context is a pretty common and innocuous variable name so this causes a very large number of our specs to not work with this spec.

To repro

Use this spec

RSpec.describe("Context bug") do
  let(:context) { "foo" }

  before do
    context
  end

  it("bar") { expect(true) }
end

Observe broken awareness of the spec, lack of code lens support, and incorrect labeling of the context variable as a spec.

The cause

There is a validation to see if a node is actually a test group, but it passes too easily. It's treated as a node group even if there is no block associated with it. In addition, there was no validation performed in test_discovery,

The fix

Actually ensure the node has a block before allowing it to be treated as a test group.

Behold

[nathanscottdaniels]

@st0012 anybody home? 👀

[st0012]

Can you add some regression tests covering these cases?

[nathanscottdaniels]

Can you add some regression tests covering these cases?

Done! 🫡

[st0012]

Thank you!