feat: add >> raises(...) for exception stubbing in interactions

[JPDuchesne]

Summary

• Introduces the outcome concept to interactions, replacing the raw return_value field. The >> operator now produces a typed outcome node (:rspock_returns or :rspock_raises) at parse time.
• The transformation generically forwards the outcome type and args to Mocha via an explicit OUTCOME_METHODS mapping — no branching or string manipulation.
• Adds OutcomeNode, ReturnsNode, and RaisesNode to the node type hierarchy for consistency with other RSpock node types.

New syntax

# Stub an exception
1 * repository.find(42) >> raises(RecordNotFound)

# With message
1 * repository.find(42) >> raises(RecordNotFound, "not found")

# With instance
1 * repository.find(42) >> raises(RecordNotFound.new("not found"))

Files changed

• lib/rspock/ast/parser/interaction_parser.rb — parse_outcome wraps >> values in typed nodes
• lib/rspock/ast/node.rb — OutcomeNode / ReturnsNode / RaisesNode; InteractionNode#outcome replaces #return_value
• lib/rspock/ast/interaction_to_mocha_mock_transformation.rb — generic outcome forwarding via OUTCOME_METHODS constant
• README.md — new "Stubbing Exceptions" section, updated interaction anatomy diagram
• Tests updated and new tests added for all raises variants

Test plan

• All 189 existing tests pass (no regressions)
• New parser tests: >> raises(Ex), >> raises(Ex, msg) produce correct :rspock_raises nodes
• New transformation tests: raises(Ex), raises(Ex, msg), raises(Ex.new(msg)), with params, with range cardinality

Made with Cursor

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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