{
"comparison_replacement" => build(test_name: "returns_correct_result_at_comparison_boundary_in") do |method_name|
<<~BODY
# Test with values where the original operator and mutated operator
# produce different results (e.g., equal values for > vs >=)
result = subject.#{method_name}(boundary_value)
assert_equal expected, result
BODY
end,
"arithmetic_replacement" => build(test_name: "computes_correct_arithmetic_result_in") do |method_name|
<<~BODY
# Assert the exact numeric result, not just truthiness or sign
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"boolean_operator_replacement" => build(test_name: "returns_correct_result_when_one_condition_differs_in") do |method_name|
<<~BODY
# Use inputs where only one operand is truthy to distinguish && from ||
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"boolean_literal_replacement" => build(test_name: "returns_expected_boolean_value_from") do |method_name|
<<~BODY
# Assert the exact true/false/nil value, not just truthiness
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"negation_insertion" => build(test_name: "returns_correct_boolean_from_predicate_in") do |method_name|
<<~BODY
# Assert the exact true/false result, not just truthiness
result = subject.#{method_name}(input_value)
assert_includes [true, false], result
BODY
end,
"integer_literal" => build(test_name: "returns_exact_integer_value_from") do |method_name|
<<~BODY
# Assert the exact numeric value, not just > 0 or truthy
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"float_literal" => build(test_name: "returns_exact_float_value_from") do |method_name|
<<~BODY
# Assert the exact floating-point result
result = subject.#{method_name}(input_value)
assert_in_delta expected, result
BODY
end,
"string_literal" => build(test_name: "returns_exact_string_content_from") do |method_name|
<<~BODY
# Assert the exact string value, not just presence or non-empty
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"symbol_literal" => build(test_name: "returns_exact_symbol_from") do |method_name|
<<~BODY
# Assert the exact symbol value, not just that it is a Symbol
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"array_literal" => build(test_name: "returns_expected_array_contents_from") do |method_name|
<<~BODY
# Assert the exact array elements, not just non-empty or truthy
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"hash_literal" => build(test_name: "returns_expected_hash_contents_from") do |method_name|
<<~BODY
# Assert the exact keys and values, not just non-empty or truthy
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"collection_replacement" => build(test_name: "uses_return_value_of_collection_operation_in") do |method_name|
<<~BODY
# Assert the return value of the collection method, not just side effects
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"conditional_negation" => build(test_name: "exercises_both_branches_of_conditional_in") do |method_name|
<<~BODY
# Test with inputs that make the condition true AND false
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"conditional_branch" => build(test_name: "exercises_removed_branch_of_conditional_in") do |method_name|
<<~BODY
# Test with inputs that trigger the branch removed by this mutation
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"statement_deletion" => build(test_name: "depends_on_side_effect_of_deleted_statement_in", action: :deleted) do |method_name|
<<~BODY
# Assert a side effect or return value that changes when this statement is removed
subject.#{method_name}(input_value)
assert_equal expected, observable_side_effect
BODY
end,
"method_body_replacement" => build(test_name: "verifies_return_value_or_side_effects_of") do |method_name|
<<~BODY
# Assert the method produces a meaningful result, not just nil
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"return_value_removal" => build(test_name: "uses_return_value_of") do |method_name|
<<~BODY
# Assert the caller depends on the return value, not just side effects
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"method_call_removal" => build(test_name: "depends_on_return_value_or_side_effect_of_call_in") do |method_name|
<<~BODY
# Assert the method call's effect is observable
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"compound_assignment" => build(test_name: "verifies_compound_assignment_side_effect_in") do |method_name|
<<~BODY
# Assert the accumulated value after the compound assignment
# The mutation changes the operator, so the final value will differ
subject.#{method_name}(input_value)
assert_equal expected, observable_side_effect
BODY
end,
"nil_replacement" => build(test_name: "asserts_nil_return_value_from") do |method_name|
<<~BODY
# Assert the method returns nil, not a substituted value
result = subject.#{method_name}(input_value)
assert_nil result
BODY
end,
"superclass_removal" => build(test_name: "depends_on_inherited_behavior_in", action: :removed_superclass) do |method_name|
<<~BODY
# Assert behavior that comes from the superclass
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"local_variable_assignment" => build(test_name: "verifies_local_variable_assignment_is_used_in") do |method_name|
<<~BODY
# Assert that the assigned variable is read later, not just the value expression
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"instance_variable_write" => build(test_name: "verifies_instance_variable_is_set_correctly_in") do |method_name|
<<~BODY
# Assert that the instance variable holds the expected value after the method runs
subject.#{method_name}(input_value)
assert_equal expected, subject.instance_variable_get(:@variable)
BODY
end,
"class_variable_write" => build(test_name: "verifies_class_variable_shared_state_in") do |method_name|
<<~BODY
# Assert that the class variable holds the expected value and affects shared state
subject.#{method_name}(input_value)
assert_equal expected, klass.class_variable_get(:@@variable)
BODY
end,
"global_variable_write" => build(test_name: "verifies_global_variable_is_set_correctly_in") do |method_name|
<<~BODY
# Assert that the global variable holds the expected value after the method runs
subject.#{method_name}(input_value)
assert_equal expected, $variable
BODY
end,
"mixin_removal" => build(test_name: "depends_on_behavior_from_included_module_in", action: :removed) do |method_name|
<<~BODY
# Assert behavior provided by the mixin
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"rescue_removal" => build(test_name: "verifies_rescue_handler_is_needed_in", action: :removed) do |method_name|
<<~BODY
# Trigger the rescued exception and assert the handler's effect
result = subject.#{method_name}(input_that_raises)
assert_equal expected, result
BODY
end,
"rescue_body_replacement" => build(test_name: "verifies_rescue_handler_produces_correct_result_in") do |method_name|
<<~BODY
# Trigger the exception and assert the rescue body's return value or side effect
result = subject.#{method_name}(input_that_raises)
assert_equal expected, result
BODY
end,
"inline_rescue" => build(test_name: "verifies_inline_rescue_fallback_value_in") do |method_name|
<<~BODY
# Trigger the exception and assert the fallback value is correct
result = subject.#{method_name}(input_that_raises)
assert_equal expected, result
BODY
end,
"ensure_removal" => build(test_name: "verifies_ensure_cleanup_runs_in", action: :removed_ensure) do |method_name|
<<~BODY
# Assert that the cleanup side effect is observable after the method runs
subject.#{method_name}(input_value)
assert_equal expected, observable_cleanup_effect
BODY
end,
"break_statement" => build(test_name: "verifies_break_exits_loop_correctly_in") do |method_name|
<<~BODY
# Assert the loop exits early and returns the expected value
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"next_statement" => build(test_name: "verifies_next_skips_iteration_correctly_in") do |method_name|
<<~BODY
# Assert the iteration is skipped and the expected value is yielded
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"redo_statement" => build(test_name: "verifies_redo_retry_logic_is_necessary_in") do |method_name|
<<~BODY
# Assert the iteration restart changes the outcome
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"bitwise_replacement" => build(test_name: "verifies_exact_bitwise_result_in") do |method_name|
<<~BODY
# Assert the exact bit-level result to distinguish &, |, and ^ operators
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"bitwise_complement" => build(test_name: "verifies_bitwise_complement_result_in") do |method_name|
<<~BODY
# Assert the exact complement (~) value, not just sign or magnitude
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"bang_method" => build(test_name: "verifies_in_place_vs_copy_semantics_matter_in") do |method_name|
<<~BODY
# Assert that the original object is or is not modified
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"zsuper_removal" => build(test_name: "verifies_inherited_behavior_from_super_in") do |method_name|
<<~BODY
# Assert that the result depends on the superclass implementation
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"explicit_super_mutation" => build(test_name: "verifies_correct_arguments_passed_to_super_in") do |method_name|
<<~BODY
# Assert the inherited method receives the expected arguments
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"index_to_fetch" => build(test_name: "distinguishes_bracket_from_fetch_for_missing_keys_in") do |method_name|
<<~BODY
# Access a missing key: [] returns nil, .fetch raises KeyError
assert_raises(KeyError) { subject.#{method_name}(collection_with_missing_key) }
BODY
end,
"index_to_dig" => build(test_name: "verifies_chained_bracket_access_returns_correct_nested_value_in") do |method_name|
<<~BODY
# Assert the nested lookup produces the expected value
result = subject.#{method_name}(nested_collection)
assert_equal expected, result
BODY
end,
"index_assignment_removal" => build(test_name: "verifies_bracket_assignment_modifies_collection_in") do |method_name|
<<~BODY
# Assert the collection contains the assigned value at the expected key after the method runs
result = subject.#{method_name}(collection)
assert_equal expected_value, result[expected_key]
BODY
end,
"pattern_matching_guard" => build(test_name: "verifies_pattern_guard_filters_correctly_in") do |method_name|
<<~BODY
# Test with input that matches the pattern but fails the guard condition
# The guard should prevent matching, routing to a different branch
result = subject.#{method_name}(input_matching_pattern_but_failing_guard)
assert_equal expected, result
BODY
end,
"pattern_matching_alternative" => build(test_name: "verifies_each_pattern_alternative_is_reachable_in") do |method_name|
<<~BODY
# Test with input that matches only one specific alternative
# Each alternative should have a dedicated test case
result = subject.#{method_name}(input_for_specific_alternative)
assert_equal expected, result
BODY
end,
"collection_return" => build(test_name: "returns_non_empty_collection_from") do |method_name|
<<~BODY
# Assert the collection has the expected elements, not just non-empty
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"scalar_return" => build(test_name: "returns_non_zero_non_empty_value_from") do |method_name|
<<~BODY
# Assert the exact scalar value, not just presence or type
result = subject.#{method_name}(input_value)
assert_equal expected, result
BODY
end,
"pattern_matching_array" => build(test_name: "verifies_each_array_pattern_element_matters_in") do |method_name|
<<~BODY
# Test with input where changing one element type causes a different match
# Each position in the array pattern should be validated
result = subject.#{method_name}(input_with_wrong_element_type)
assert_equal expected, result
BODY
end
}.freeze