cue def foo.cue -o openapi:-
cmp stdout expect-json

cue def foo.cue -o openapi+cue:-
cmp stdout expect-cue

cue def foo.cue -o openapi+yaml:-
cmp stdout expect-yaml

-- foo.cue --
Foo :: {
    a: int
    b: uint & <10
}

Bar :: {
    foo: Foo
}

-- expect-json --
{
    "openapi": "3.0.0",
    "info": {},
    "paths": {},
    "components": {
        "schemas": {
            "Foo": {
                "type": "object",
                "required": [
                    "a",
                    "b"
                ],
                "properties": {
                    "a": {
                        "type": "integer"
                    },
                    "b": {
                        "type": "integer",
                        "minimum": 0,
                        "exclusiveMaximum": 10
                    }
                }
            },
            "Bar": {
                "type": "object",
                "required": [
                    "foo"
                ],
                "properties": {
                    "foo": {
                        "$ref": "#/components/schemas/Foo"
                    }
                }
            }
        }
    }
}
-- expect-cue --
openapi: "3.0.0"
info: {}
paths: {}
components: schemas: {
	Foo: {
		type: "object"
		required: ["a", "b"]
		properties: {
			a: type: "integer"
			b: {
				type:             "integer"
				minimum:          0
				exclusiveMaximum: 10
			}
		}
	}
	Bar: {
		type: "object"
		required: ["foo"]
		properties: foo: $ref: "#/components/schemas/Foo"
	}
}
-- expect-yaml --
openapi: 3.0.0
info: {}
paths: {}
components:
    schemas:
        Foo:
            type: object
            required:
              - a
              - b
            properties:
                a:
                    type: integer
                b:
                    type: integer
                    minimum: 0
                    exclusiveMaximum: 10
        Bar:
            type: object
            required:
              - foo
            properties:
                foo:
                    $ref: '#/components/schemas/Foo'