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Support for release builds
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We were under the impression that XCTestDynamicOverlay's code could lead
to App Store rejections, but it sounds like that report was a false
positive.

Let's lift our current restriction to unlock the ability to use
XCTestDynamicOverlay in release builds.
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@stephencelis
stephencelis committed Apr 13, 2023
1 parent 4af50b3 commit 1b38fe8
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3 changes: 0 additions & 3 deletions README.md
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Expand Up @@ -41,9 +41,6 @@ import XCTestDynamicOverlay // ✅

…and your application or library will continue to compile just fine.

> ⚠️ Important: The dynamically loaded `XCTFail` is only available in `DEBUG` builds in order
to prevent App Store rejections due to runtime loading of symbols.


## Example

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42 changes: 18 additions & 24 deletions Sources/XCTestDynamicOverlay/Internal/XCTCurrentTestCase.swift
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@@ -1,28 +1,22 @@
#if DEBUG
#if canImport(ObjectiveC)
import Foundation
#if canImport(ObjectiveC)
import Foundation

@_spi(CurrentTestCase) public var XCTCurrentTestCase: AnyObject? {
guard
let XCTestObservationCenter = NSClassFromString("XCTestObservationCenter"),
let XCTestObservationCenter = XCTestObservationCenter as Any as? NSObjectProtocol,
let shared = XCTestObservationCenter.perform(Selector(("sharedTestObservationCenter")))?
.takeUnretainedValue(),
let observers = shared.perform(Selector(("observers")))?
.takeUnretainedValue() as? [AnyObject],
let observer =
observers
.first(where: { NSStringFromClass(type(of: $0)) == "XCTestMisuseObserver" }),
let currentTestCase = observer.perform(Selector(("currentTestCase")))?
.takeUnretainedValue()
else { return nil }
return currentTestCase
}
#else
@_spi(CurrentTestCase) public var XCTCurrentTestCase: AnyObject? {
nil
}
#endif
@_spi(CurrentTestCase) public var XCTCurrentTestCase: AnyObject? {
guard
let XCTestObservationCenter = NSClassFromString("XCTestObservationCenter"),
let XCTestObservationCenter = XCTestObservationCenter as Any as? NSObjectProtocol,
let shared = XCTestObservationCenter.perform(Selector(("sharedTestObservationCenter")))?
.takeUnretainedValue(),
let observers = shared.perform(Selector(("observers")))?
.takeUnretainedValue() as? [AnyObject],
let observer =
observers
.first(where: { NSStringFromClass(type(of: $0)) == "XCTestMisuseObserver" }),
let currentTestCase = observer.perform(Selector(("currentTestCase")))?
.takeUnretainedValue()
else { return nil }
return currentTestCase
}
#else
@_spi(CurrentTestCase) public var XCTCurrentTestCase: AnyObject? {
nil
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238 changes: 105 additions & 133 deletions Sources/XCTestDynamicOverlay/XCTFail.swift
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@@ -1,159 +1,131 @@
import Foundation

#if DEBUG
#if canImport(ObjectiveC)
/// This function generates a failure immediately and unconditionally.
///
/// Dynamically creates and records an `XCTIssue` under the hood that captures the source code
/// context of the caller. Useful for defining assertion helpers that fail in indirect code
/// paths, where the `file` and `line` of the failure have not been realized.
///
/// - Parameter message: An optional description of the assertion, for inclusion in test
/// results.
@_disfavoredOverload
public func XCTFail(_ message: String = "") {
var message = message
attachHostApplicationWarningIfNeeded(&message)
guard
let currentTestCase = XCTCurrentTestCase,
let XCTIssue = NSClassFromString("XCTIssue")
as Any as? NSObjectProtocol,
let alloc = XCTIssue.perform(NSSelectorFromString("alloc"))?
.takeUnretainedValue(),
let issue =
alloc
.perform(
Selector(("initWithType:compactDescription:")),
with: 0,
with: message.isEmpty ? "failed" : message
)?
.takeUnretainedValue()
else {
if !_XCTIsTesting {
runtimeWarn(message)
}
return
#if canImport(ObjectiveC)
/// This function generates a failure immediately and unconditionally.
///
/// Dynamically creates and records an `XCTIssue` under the hood that captures the source code
/// context of the caller. Useful for defining assertion helpers that fail in indirect code
/// paths, where the `file` and `line` of the failure have not been realized.
///
/// - Parameter message: An optional description of the assertion, for inclusion in test
/// results.
@_disfavoredOverload
public func XCTFail(_ message: String = "") {
var message = message
attachHostApplicationWarningIfNeeded(&message)
guard
let currentTestCase = XCTCurrentTestCase,
let XCTIssue = NSClassFromString("XCTIssue")
as Any as? NSObjectProtocol,
let alloc = XCTIssue.perform(NSSelectorFromString("alloc"))?
.takeUnretainedValue(),
let issue =
alloc
.perform(
Selector(("initWithType:compactDescription:")),
with: 0,
with: message.isEmpty ? "failed" : message
)?
.takeUnretainedValue()
else {
if !_XCTIsTesting {
runtimeWarn(message)
}
_ = currentTestCase.perform(Selector(("recordIssue:")), with: issue)
return
}
_ = currentTestCase.perform(Selector(("recordIssue:")), with: issue)
}

/// This function generates a failure immediately and unconditionally.
///
/// Dynamically calls `XCTFail` with the given file and line. Useful for defining assertion
/// helpers that have the source code context at hand and want to highlight the direct caller
/// of the helper.
///
/// - Parameter message: An optional description of the assertion, for inclusion in test
/// results.
@_disfavoredOverload
public func XCTFail(_ message: String = "", file: StaticString, line: UInt) {
var message = message
attachHostApplicationWarningIfNeeded(&message)
_XCTFailureHandler(nil, true, "\(file)", line, "\(message.isEmpty ? "failed" : message)", nil)
}
/// This function generates a failure immediately and unconditionally.
///
/// Dynamically calls `XCTFail` with the given file and line. Useful for defining assertion
/// helpers that have the source code context at hand and want to highlight the direct caller
/// of the helper.
///
/// - Parameter message: An optional description of the assertion, for inclusion in test
/// results.
@_disfavoredOverload
public func XCTFail(_ message: String = "", file: StaticString, line: UInt) {
var message = message
attachHostApplicationWarningIfNeeded(&message)
_XCTFailureHandler(nil, true, "\(file)", line, "\(message.isEmpty ? "failed" : message)", nil)
}

private typealias XCTFailureHandler = @convention(c) (
AnyObject?, Bool, UnsafePointer<CChar>, UInt, String, String?
) -> Void
private let _XCTFailureHandler = unsafeBitCast(
dlsym(dlopen(nil, RTLD_LAZY), "_XCTFailureHandler"),
to: XCTFailureHandler.self
)
private typealias XCTFailureHandler = @convention(c) (
AnyObject?, Bool, UnsafePointer<CChar>, UInt, String, String?
) -> Void
private let _XCTFailureHandler = unsafeBitCast(
dlsym(dlopen(nil, RTLD_LAZY), "_XCTFailureHandler"),
to: XCTFailureHandler.self
)

private func attachHostApplicationWarningIfNeeded(_ message: inout String) {
guard
_XCTIsTesting,
Bundle.main.bundleIdentifier != "com.apple.dt.xctest.tool"
else { return }
private func attachHostApplicationWarningIfNeeded(_ message: inout String) {
guard
_XCTIsTesting,
Bundle.main.bundleIdentifier != "com.apple.dt.xctest.tool"
else { return }

let callStack = Thread.callStackSymbols
let callStack = Thread.callStackSymbols

// Detect when synchronous test exists in stack.
guard callStack.allSatisfy({ frame in !frame.contains(" XCTestCore ") })
else { return }
// Detect when synchronous test exists in stack.
guard callStack.allSatisfy({ frame in !frame.contains(" XCTestCore ") })
else { return }

// Detect when asynchronous test exists in stack.
guard callStack.allSatisfy({ frame in !isTestFrame(frame) })
else { return }
// Detect when asynchronous test exists in stack.
guard callStack.allSatisfy({ frame in !isTestFrame(frame) })
else { return }

if !message.contains(where: \.isNewline) {
message.append(" …")
}
if !message.contains(where: \.isNewline) {
message.append(" …")
}

message.append(
"""
message.append(
"""
━━┉┅
Note: This failure was emitted from tests running in a host application\
\(Bundle.main.bundleIdentifier.map { " (\($0))" } ?? "").
━━┉┅
Note: This failure was emitted from tests running in a host application\
\(Bundle.main.bundleIdentifier.map { " (\($0))" } ?? "").
This can lead to false positives, where failures could have emitted from live application \
code at launch time, and not from the current test.
This can lead to false positives, where failures could have emitted from live application \
code at launch time, and not from the current test.
For more information (and workarounds), see "Testing gotchas":
For more information (and workarounds), see "Testing gotchas":
https://pointfreeco.github.io/swift-dependencies/main/documentation/dependencies/testing#Testing-gotchas
"""
)
}
https://pointfreeco.github.io/swift-dependencies/main/documentation/dependencies/testing#Testing-gotchas
"""
)
}

func isTestFrame(_ frame: String) -> Bool {
// Regular expression to detect and demangle an XCTest case frame:
//
// 1. `(?<=\$s)`: Starts with "$s" (stable mangling)
// 2. `\d{1,3}`: Some numbers (the class name length or the module name length)
// 3. `.*`: The class name, or module name + class name length + class name
// 4. `C`: The class type identifier
// 5. `(?=\d{1,3}test.*yy(Ya)?K?F)`: The function name length, a function that starts with
// `test`, has no arguments (`y`), returns Void (`y`), and is a function (`F`), potentially
// async (`Ya`), throwing (`K`), or both.
let mangledTestFrame = #"(?<=\$s)\d{1,3}.*C(?=\d{1,3}test.*yy(Ya)?K?F)"#

guard let XCTestCase = NSClassFromString("XCTestCase")
else { return false }

return frame.range(of: mangledTestFrame, options: .regularExpression)
.map {
(_typeByName(String(frame[$0])) as? NSObject.Type)?.isSubclass(of: XCTestCase) ?? false
}
?? false
}
#elseif canImport(XCTest)
// NB: It seems to be safe to import XCTest on Linux
@_exported import func XCTest.XCTFail
#else
@_disfavoredOverload
public func XCTFail(_ message: String = "") {
print(noop(message: message))
}
@_disfavoredOverload
public func XCTFail(_ message: String = "", file: StaticString, line: UInt) {
print(noop(message: message, file: file, line: line))
}
#endif
func isTestFrame(_ frame: String) -> Bool {
// Regular expression to detect and demangle an XCTest case frame:
//
// 1. `(?<=\$s)`: Starts with "$s" (stable mangling)
// 2. `\d{1,3}`: Some numbers (the class name length or the module name length)
// 3. `.*`: The class name, or module name + class name length + class name
// 4. `C`: The class type identifier
// 5. `(?=\d{1,3}test.*yy(Ya)?K?F)`: The function name length, a function that starts with
// `test`, has no arguments (`y`), returns Void (`y`), and is a function (`F`), potentially
// async (`Ya`), throwing (`K`), or both.
let mangledTestFrame = #"(?<=\$s)\d{1,3}.*C(?=\d{1,3}test.*yy(Ya)?K?F)"#

guard let XCTestCase = NSClassFromString("XCTestCase")
else { return false }

return frame.range(of: mangledTestFrame, options: .regularExpression)
.map {
(_typeByName(String(frame[$0])) as? NSObject.Type)?.isSubclass(of: XCTestCase) ?? false
}
?? false
}
#elseif canImport(XCTest)
// NB: It seems to be safe to import XCTest on Linux
@_exported import func XCTest.XCTFail
#else
/// This function generates a failure immediately and unconditionally.
///
/// Dynamically creates and records an `XCTIssue` under the hood that captures the source code
/// context of the caller. Useful for defining assertion helpers that fail in indirect code
/// paths, where the `file` and `line` of the failure have not been realized.
///
/// - Parameter message: An optional description of the assertion, for inclusion in test
/// results.
@_disfavoredOverload
public func XCTFail(_ message: String = "") {
print(noop(message: message))
}

/// This function generates a failure immediately and unconditionally.
///
/// Dynamically creates and records an `XCTIssue` under the hood that captures the source code
/// context of the caller. Useful for defining assertion helpers that fail in indirect code
/// paths, where the `file` and `line` of the failure have not been realized.
///
/// - Parameter message: An optional description of the assertion, for inclusion in test
/// results.
@_disfavoredOverload
public func XCTFail(_ message: String = "", file: StaticString, line: UInt) {
print(noop(message: message, file: file, line: line))
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2 changes: 1 addition & 1 deletion Tests/XCTestDynamicOverlayTests/HostAppDetectionTests.swift
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@@ -1,4 +1,4 @@
#if DEBUG && canImport(ObjectiveC)
#if canImport(ObjectiveC)
import XCTest

@testable import XCTestDynamicOverlay
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