describe :symbol causes the subject to be "symbol", not :symbol

[myronmarston]

Discovered by @sferik in rspec/rspec-expectations#405.

[JonRowe]

I'd expect that behaviour, as we generally expect it to be a string or class, not an instance which I guess a symbol is. I suppose we could special case special primitives but is it worth it?

[sferik]

It seems to work for other instances, just not symbols:

obj = Object.new

describe obj do
  it { expect(subject).to eq(obj) }
end

Can you point to the specific code that’s causing this bug (i.e. where the special case would need to be inserted)? I’m new to the codebase and am not quite sure where this is happening.

[myronmarston]

I'd expect that behaviour, as we generally expect it to be a string or class, not an instance which I guess a symbol is. I suppose we could special case special primitives but is it worth it?

Classes and strings are most common, but most other built-in types work. For example, the following all work:

describe 3 do
  it { is_expected.to be_between(2, 4) }
end

describe 3.1 do
  it { is_expected.to be_a(Float) }
end

describe ["foo"] do
  it { is_expected.to eq ["foo"] }
end

describe (1..10) do
  it { is_expected.to be_a(Range) }
end

describe Date.today do
  it { is_expected.to be_a(Date) }
end

describe Time.now do
  it { is_expected.to be_a(Time) }
end

It looks like hashes don't, however:

describe({:foo => 3, :bar => 2}) do
  it { is_expected.to be_a(Hash) }
end

...fails with expected "" to be a kind of Hash. I suspect that may have to do with it interpretting the hash as metadata.

@sferik -- implicit subject is defined in memoized_helpers.rb. That in turn uses described_class or description, which is defined to get their values from metadata, which turns out to have a special case for symbols.

[sferik]

IMHO, the correct solution is to remove the || Symbol === candidate special case in RSpec 3.

Perhaps it even makes sense to remove GroupMetadataHash altogether?

[JonRowe]

Interesting, I'd guess it's to maintain the Symbol / String parity used elsewhere. (E.g. Symbols are often used as frozen/special strings). I see no harm in removing this though...