Fix member-level @available attributes hoisted to mock class declaration

[farkasseb]

Summary

Member-level behavioral @available attributes (noasync, deprecated) were concatenated and hoisted to the mock class declaration instead of staying on the individual generated members.

Example

/// @mockable
public protocol StorageInput: Sendable {
    func put(_ value: String, for key: String) async throws
    func string(for key: String) async throws -> String

    @available(*, noasync)
    @available(*, deprecated, message: "Use put(_:for:) async throws")
    @discardableResult func set(_ value: String, for key: String) -> Result<Void, Error>

    @available(*, noasync)
    @available(*, deprecated, message: "Use string(for:) async throws")
    func string(for key: String) -> Result<String, Error>
}

Before — attributes from all deprecated members are concatenated onto the class declaration, causing a build error:

@available(*, noasync)
    @available(*, deprecated, message: "Use put(_:for:) async throws")
    @discardableResult @available(*, noasync)
    @available(*, deprecated, message: "Use string(for:) async throws")
public final class StorageInputMock: StorageInput, @unchecked Sendable {
    public var setCallCount: Int { ... }
    public func set(_ value: String, for key: String) -> Result<Void, Error> { ... }
    public func string(for key: String) -> Result<String, Error> { ... }
}

After — only the protocol-conforming methods carry their own attributes:

public final class StorageInputMock: StorageInput, @unchecked Sendable {
    public var setCallCount: Int { ... }
    public var setHandler: (...)? { ... }
    @available(*, noasync)
    @available(*, deprecated, message: "Use put(_:for:) async throws")
    public func set(_ value: String, for key: String) -> Result<Void, Error> { ... }

    public var stringForCallCount: Int { ... }
    public var stringForHandler: (...)? { ... }
    @available(*, noasync)
    @available(*, deprecated, message: "Use string(for:) async throws")
    public func string(for key: String) -> Result<String, Error> { ... }
}

Attributes are placed only on the protocol-conforming declaration (funcs, vars, subscripts, and inits), not on mock infrastructure (callCount, handler, state). This keeps test setup and inspection clean — configuring a handler for a deprecated method won't trigger deprecation warnings, and noasync won't restrict mock configuration from async tests.

One deliberate consequence: a deprecated stored property still produces a deprecation warning inside the generated convenience init (self.data = data) — seeding a deprecated property is deprecated usage, and the warning correctly points at the protocol still carrying the deprecated member.

Note on platform availability

Existence-gating availability — @available(iOS 16, *), introduced:, obsoleted:, unavailable — continues to hoist to the class declaration, same as before this fix, since the mock's infrastructure references the member's types unconditionally. Extended-form platform-scoped deprecations (@available(iOS, deprecated: 12.0)) are warning-only, so they stay on the member like their *-form counterparts; when a single attribute combines both (@available(iOS, introduced: 10.0, deprecated: 12.0)), gating wins and it hoists.

Two smaller behavior notes: non-@available attributes no longer leak onto the class alongside a hoisted member attribute (only @available is ever hoisted), and behavioral attributes on associatedtypes are deliberately dropped, since the generated typealias is referenced throughout the mock's own infrastructure.

Hoisted class-level attributes are now deduplicated per individual attribute and rendered in member source order (order-preserving uniqued()); previously an unordered Set join made the order vary between executions.

Test plan

• 4 focused test fixtures (compiled @Fixture mocks, so expected output is conformance-checked by the compiler): deprecated members on the original reported issue, protocol-level + member-level @available coexistence, multiple attributes on one method, and platform attributes hoisting to the class
• All 155 tests pass

🤖 Generated with Claude Code

[sidepelican]

It looks good, but there are several improvements.

• Create a Attribute struct and store the parsed information from AttributeList within [Attribute].
  • Model should have this as var attributes: [Attribute] instead of [String].
  • Add an applyAttributeTemplate extension to the [Attribute] type that functions similarly to the current asAttributePrefix implementation.
  • Remove isBehavioralAvailable, behavioralAvailableDescriptions, platformAvailableString, and platformAvailableDescriptions, and add computed properties to Attribute as needed
  • When generating objects like VariableModel, pass the attributes using syntax like attributes.filter(\.isAvailable).
• Remove the redundant attributes parameter from applyFooTemplate and instead reference it directly from self.
• Avoid adding unnecessary tests. Focus only on the minimum required tests to verify functionality.
• Ensure that the generated output remains consistent across executions.

[farkasseb]

Thank you so much for the review @sidepelican ! I tried to implement what you were suggesting, please let me know what you think.

Regarding the excessive testing, the trim is fine by me, but to calibrate future PRs: how do you weigh scenario coverage against fixture maintenance? My instinct was that more covered scenarios is better.

[sidepelican]

Too many tests can increase maintenance costs.
When the purpose of a test is unclear, it can end up confusing developers.

[sidepelican]

LGTM. Since the parse logic felt a bit complex, I refactored it into a simpler version here. I believe this should be sufficient.
Thanks.