design-md-consolidation 3.4: add design_schema_drift.rs — exhaustive-match drift test for ast.rs vs DESIGN.md §Data-model

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2026-05-10 12:51:39 +02:00
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//! Sweep 3 / Task 4: drift detection between ast.rs and `docs/DESIGN.md`
//! §"Data model".
//!
//! DESIGN.md is the canonical schema source-of-truth. Every AST enum
//! (`Term`, `Pattern`, `Type`, `Def`, `Literal`, `ParamMode`) must have a
//! JSON-schema anchor (e.g. `"t": "lit"`, `"k": "fn"`) present in that
//! document. These tests enforce the property.
//!
//! The exhaustive `match` per enum is the load-bearing mechanism: adding a
//! new variant without a matching arm fails compilation before the test runs.
//! Once the variant is matched, the test asserts the anchor is present in
//! DESIGN.md.
use ailang_core::ast::{
ClassDef, ClassMethod, Constraint, ConstDef, Ctor, Def, FnDef, InstanceDef,
InstanceMethod, Literal, Pattern, ParamMode, Suppress, Term, Type, TypeDef,
};
const DESIGN_MD: &str = include_str!("../../../docs/DESIGN.md");
/// Every `Term` variant must have its JSON-schema anchor present in
/// DESIGN.md §"Data model". An LLM author cannot produce a term variant
/// whose `"t"` tag is absent from the canonical schema document.
#[test]
fn design_md_anchors_every_term_variant() {
let exemplars: Vec<(&str, Term)> = vec![
(
r#""t": "lit""#,
Term::Lit { lit: Literal::Unit },
),
(
r#""t": "var""#,
Term::Var { name: "x".into() },
),
(
r#""t": "app""#,
Term::App {
callee: Box::new(Term::Var { name: "f".into() }),
args: vec![],
tail: false,
},
),
(
r#""t": "let""#,
Term::Let {
name: "x".into(),
value: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
body: Box::new(Term::Var { name: "x".into() }),
},
),
(
r#""t": "letrec""#,
Term::LetRec {
name: "f".into(),
ty: Type::fn_implicit(vec![], Type::int(), vec![]),
params: vec![],
body: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
in_term: Box::new(Term::Var { name: "f".into() }),
},
),
(
r#""t": "if""#,
Term::If {
cond: Box::new(Term::Lit { lit: Literal::Bool { value: true } }),
then: Box::new(Term::Lit { lit: Literal::Int { value: 1 } }),
else_: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
},
),
(
r#""t": "do""#,
Term::Do {
op: "io/print_int".into(),
args: vec![],
tail: false,
},
),
(
r#""t": "ctor""#,
Term::Ctor {
type_name: "List".into(),
ctor: "Nil".into(),
args: vec![],
},
),
(
r#""t": "match""#,
Term::Match {
scrutinee: Box::new(Term::Var { name: "x".into() }),
arms: vec![],
},
),
(
r#""t": "lam""#,
Term::Lam {
params: vec![],
param_tys: vec![],
ret_ty: Box::new(Type::int()),
effects: vec![],
body: Box::new(Term::Lit { lit: Literal::Int { value: 0 } }),
},
),
(
r#""t": "seq""#,
Term::Seq {
lhs: Box::new(Term::Var { name: "a".into() }),
rhs: Box::new(Term::Var { name: "b".into() }),
},
),
(
r#""t": "clone""#,
Term::Clone {
value: Box::new(Term::Var { name: "x".into() }),
},
),
(
r#""t": "reuse-as""#,
Term::ReuseAs {
source: Box::new(Term::Var { name: "x".into() }),
body: Box::new(Term::Var { name: "y".into() }),
},
),
];
for (anchor, term) in exemplars {
// Exhaustive match: compiler rejects this file if a new Term
// variant lacks an arm, catching drift at compile time.
let _: &'static str = match term {
Term::Lit { .. } => "lit",
Term::Var { .. } => "var",
Term::App { .. } => "app",
Term::Let { .. } => "let",
Term::LetRec { .. } => "letrec",
Term::If { .. } => "if",
Term::Do { .. } => "do",
Term::Ctor { .. } => "ctor",
Term::Match { .. } => "match",
Term::Lam { .. } => "lam",
Term::Seq { .. } => "seq",
Term::Clone { .. } => "clone",
Term::ReuseAs { .. } => "reuse-as",
};
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing anchor `{anchor}` for a Term variant — \
add it to docs/DESIGN.md"
);
}
}
/// Every `Pattern` variant must have its JSON-schema anchor present in
/// DESIGN.md §"Data model". Missing anchors mean an LLM cannot produce
/// the corresponding pattern form.
#[test]
fn design_md_anchors_every_pattern_variant() {
let exemplars: Vec<(&str, Pattern)> = vec![
(r#""p": "wild""#, Pattern::Wild),
(r#""p": "var""#, Pattern::Var { name: "x".into() }),
(r#""p": "lit""#, Pattern::Lit { lit: Literal::Int { value: 0 } }),
(
r#""p": "ctor""#,
Pattern::Ctor { ctor: "Nil".into(), fields: vec![] },
),
];
for (anchor, pat) in exemplars {
let _: &'static str = match pat {
Pattern::Wild => "wild",
Pattern::Var { .. } => "var",
Pattern::Lit { .. } => "lit",
Pattern::Ctor { .. } => "ctor",
};
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing anchor `{anchor}` for a Pattern variant"
);
}
}
/// Every `Type` variant must have its JSON-schema anchor present in
/// DESIGN.md §"Data model". The `"k"` discriminator is load-bearing for
/// the codegen and typechecker; an LLM must know all four forms.
#[test]
fn design_md_anchors_every_type_variant() {
let exemplars: Vec<(&str, Type)> = vec![
(r#""k": "con""#, Type::int()),
(r#""k": "fn""#, Type::fn_implicit(vec![], Type::unit(), vec![])),
(r#""k": "var""#, Type::Var { name: "a".into() }),
(
r#""k": "forall""#,
Type::Forall {
vars: vec!["a".into()],
constraints: vec![],
body: Box::new(Type::Var { name: "a".into() }),
},
),
];
for (anchor, ty) in exemplars {
let _: &'static str = match ty {
Type::Con { .. } => "con",
Type::Fn { .. } => "fn",
Type::Var { .. } => "var",
Type::Forall { .. } => "forall",
};
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing anchor `{anchor}` for a Type variant"
);
}
}
/// Every `Literal` variant must have its JSON-schema anchor present in
/// DESIGN.md §"Data model". The `"kind"` discriminator identifies the
/// literal type; an LLM cannot produce a literal it hasn't seen in the
/// schema.
#[test]
fn design_md_anchors_every_literal_variant() {
let exemplars: Vec<(&str, Literal)> = vec![
(r#""kind": "int""#, Literal::Int { value: 0 }),
(r#""kind": "bool""#, Literal::Bool { value: true }),
(r#""kind": "str""#, Literal::Str { value: "x".into() }),
(r#""kind": "unit""#, Literal::Unit),
];
for (anchor, lit) in exemplars {
let _: &'static str = match lit {
Literal::Int { .. } => "int",
Literal::Bool { .. } => "bool",
Literal::Str { .. } => "str",
Literal::Unit => "unit",
};
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing anchor `{anchor}` for a Literal variant"
);
}
}
/// Every `Def` kind must have its JSON-schema anchor present in
/// DESIGN.md §"Data model". All five kinds (`fn`, `const`, `type`,
/// `ClassDef`, `InstanceDef`) must be documented so an LLM can write
/// any kind of top-level definition.
#[test]
fn design_md_anchors_every_def_kind() {
let fn_def = FnDef {
name: "f".into(),
doc: None,
suppress: vec![],
ty: Type::fn_implicit(vec![], Type::int(), vec![]),
params: vec![],
body: Term::Lit { lit: Literal::Int { value: 0 } },
};
let const_def = ConstDef {
name: "k".into(),
doc: None,
ty: Type::int(),
value: Term::Lit { lit: Literal::Int { value: 0 } },
};
let type_def = TypeDef {
name: "T".into(),
doc: None,
vars: vec![],
ctors: vec![Ctor { name: "C".into(), fields: vec![] }],
drop_iterative: false,
};
let class_def = ClassDef {
name: "Show".into(),
param: "a".into(),
superclass: None,
methods: vec![ClassMethod {
name: "show".into(),
ty: Type::fn_implicit(vec![Type::Var { name: "a".into() }], Type::str_(), vec![]),
default: None,
}],
doc: None,
};
let instance_def = InstanceDef {
class: "Show".into(),
type_: Type::int(),
methods: vec![InstanceMethod {
name: "show".into(),
body: Term::Lit { lit: Literal::Str { value: "0".into() } },
}],
doc: None,
};
let exemplars: Vec<(&str, Def)> = vec![
(r#""kind": "fn""#, Def::Fn(fn_def)),
(r#""kind": "const""#, Def::Const(const_def)),
(r#""kind": "type""#, Def::Type(type_def)),
(r#""kind": "ClassDef""#, Def::Class(class_def)),
(r#""kind": "InstanceDef""#, Def::Instance(instance_def)),
];
for (anchor, def) in exemplars {
let _: &'static str = match def {
Def::Fn(_) => "fn",
Def::Const(_) => "const",
Def::Type(_) => "type",
Def::Class(_) => "class",
Def::Instance(_) => "instance",
};
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing anchor `{anchor}` for a Def kind"
);
}
}
/// Every `ParamMode` variant must have its serialized string form present
/// in DESIGN.md §"Data model". The mode annotations are load-bearing for
/// ownership checking; an LLM author must know all three forms.
#[test]
fn design_md_anchors_every_parammode_variant() {
let exemplars: Vec<(&str, ParamMode)> = vec![
(r#""implicit""#, ParamMode::Implicit),
(r#""own""#, ParamMode::Own),
(r#""borrow""#, ParamMode::Borrow),
];
for (anchor, mode) in exemplars {
let _: &'static str = match mode {
ParamMode::Implicit => "implicit",
ParamMode::Own => "own",
ParamMode::Borrow => "borrow",
};
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing anchor `{anchor}` for a ParamMode variant"
);
}
}
/// Nested struct key anchors must be present in DESIGN.md §"Data model".
/// These keys appear inside `Suppress`, `ClassMethod`, `InstanceMethod`,
/// and `Type::Forall` — they are not discriminators but they ARE part
/// of the canonical JSON schema and must remain documented.
#[test]
fn design_md_anchors_nested_struct_keys() {
// Constructors exercised here ensure ast.rs field names are correct.
let _ = Suppress { code: "x".into(), because: "y".into() };
let _ = ClassMethod {
name: "m".into(),
ty: Type::fn_implicit(vec![], Type::int(), vec![]),
default: None,
};
let _ = InstanceMethod {
name: "m".into(),
body: Term::Lit { lit: Literal::Unit },
};
let _ = Constraint {
class: "Show".into(),
type_: Type::int(),
};
let anchors = [
r#""code""#,
r#""because""#,
r#""methods""#,
r#""constraints""#,
];
for anchor in anchors {
assert!(
DESIGN_MD.contains(anchor),
"DESIGN.md §Data-model is missing nested-struct-key anchor `{anchor}`"
);
}
}