Module: Hecks::Fuzzing::InvalidValueGenerator

Defined in:
lib/hecks/fuzzing/invalid_value_generator.rb

Overview

A value that is DELIBERATELY THE WRONG SHAPE for the attribute it is handed to — the sibling of ValueGenerator, which only ever builds values that satisfy a declared type.

That limit is why the fuzzer could not reach the space a hand-written adversarial corpus covers. spec/corpus/banking.json got there one step at a time, by hand : a value object where an Integer is declared, a Float where an Integer is declared, a numeral wearing quotes, an attribute missing entirely, an attribute the command never declared. One of those — a hash reaching a refusal message — is the exact shape that exposed refusal wording drift (a composite rendered with inspect at one site and JSON at another — Rendering's whole story), and no generated value could ever have produced it.

These are expected to be REFUSED, and that is the point : a refusal is an answer, and its wording is pinned byte-for-byte. The bugs live in the sentence, not in the happy path.

Constant Summary collapse

KINDS =

Each kind names a real confusion, not random noise. Ordered roughly by how often this codebase has actually been bitten by it.

%i[
  object_for_scalar
  scalar_for_object
  float_for_integer
  numeral_string
  array_for_scalar
  boolean_for_string
  null
].freeze

Class Method Summary collapse

Class Method Details

.build(kind, attribute, aggregate, random:) ⇒ Object 



52
53
54
55
56
57
58
59
60
61
62
 
# File 'lib/hecks/fuzzing/invalid_value_generator.rb', line 52

def build(kind, attribute, aggregate, random:)
  case kind
  when :object_for_scalar then { "cents" => random.rand(1..1000) }
  when :scalar_for_object then scalar_for(attribute, aggregate, random: random)
  when :float_for_integer then random.rand(1.0..100.0).round(2)
  when :numeral_string    then random.rand(1..1000).to_s
  when :array_for_scalar  then [random.rand(1..10), random.rand(1..10)]
  when :boolean_for_string then random.rand(2).zero?
  else nil
  end
end

.corrupt(attribute, aggregate, random:) ⇒ Object 



35
36
37
38
 
# File 'lib/hecks/fuzzing/invalid_value_generator.rb', line 35

def corrupt(attribute, aggregate, random:)
  kind = kinds_for(attribute, aggregate).sample(random: random)
  build(kind, attribute, aggregate, random: random)
end

.kinds_for(attribute, aggregate) ⇒ Object

Only the confusions that MEAN anything for this attribute. Offering scalar_for_object for a plain Integer would just be a second spelling of numeral_string, and a kind that cannot be wrong for the attribute it is handed teaches the corpus nothing.



44
45
46
47
48
49
50
 
# File 'lib/hecks/fuzzing/invalid_value_generator.rb', line 44

def kinds_for(attribute, aggregate)
  value_object = aggregate.value_object(attribute.type.to_s)
  return %i[scalar_for_object array_for_scalar null] if value_object
  return %i[object_for_scalar float_for_integer numeral_string array_for_scalar null] if attribute.type.to_s == "Integer"

  %i[object_for_scalar array_for_scalar boolean_for_string null]
end

.scalar_for(attribute, aggregate, random:) ⇒ Object

A bare scalar where a value object is declared. A SINGLE-FIELD value object legitimately accepts one (that is the standing-in rule every domain relies on), so the interesting case is a value object with SEVERAL fields, where a scalar cannot stand for anything and the refusal has to say so.



68
69
70
71
72
73
74
75
 
# File 'lib/hecks/fuzzing/invalid_value_generator.rb', line 68

def scalar_for(attribute, aggregate, random:)
  value_object = aggregate.value_object(attribute.type.to_s)
  return "a bare scalar" unless value_object && value_object.attributes.size == 1

  # One field, so a scalar is legal — corrupt the FIELD's own type instead,
  # which is still a shape the attribute cannot accept.
  { value_object.attributes.first.name.to_s => ["nested", "array"] }
end

.undeclared_argument(random:) ⇒ Object

An attribute the command never declared. refuse_unknown_arguments is a real dispatch step (Vocabulary::AggregateDispatchOrder), and nothing generated had ever exercised it.



80
81
82
83
 
# File 'lib/hecks/fuzzing/invalid_value_generator.rb', line 80

def undeclared_argument(random:)
  name = %w[colour flavour rank note].sample(random: random)
  [name, %w[red loud third scribbled].sample(random: random)]
end