Why can't code inside unit tests find bundle resources?
When the unit test harness runs your code, your unit test bundle is NOT the main bundle.
Even though you are running tests, not your application, your application bundle is still the main bundle. (Presumably, this prevents the code you are testing from searching the wrong bundle.) Thus, if you add a resource file to the unit test bundle, you won't find it if search the main bundle. If you replace the above line with:
NSBundle *bundle = [NSBundle bundleForClass:[self class]];
NSString *path = [bundle pathForResource:@"foo" ofType:@"txt"];
Then your code will search the bundle that your unit test class is in, and everything will be fine.
A Swift implementation:
Swift 2
let testBundle = NSBundle(forClass: self.dynamicType)
let fileURL = testBundle.URLForResource("imageName", withExtension: "png")
XCTAssertNotNil(fileURL)
Swift 3, Swift 4
let testBundle = Bundle(for: type(of: self))
let filePath = testBundle.path(forResource: "imageName", ofType: "png")
XCTAssertNotNil(filePath)
Bundle provides ways to discover the main and test paths for your configuration:
@testable import Example
class ExampleTests: XCTestCase {
func testExample() {
let bundleMain = Bundle.main
let bundleDoingTest = Bundle(for: type(of: self ))
let bundleBeingTested = Bundle(identifier: "com.example.Example")!
print("bundleMain.bundlePath : \(bundleMain.bundlePath)")
// …/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/Library/Xcode/Agents
print("bundleDoingTest.bundlePath : \(bundleDoingTest.bundlePath)")
// …/PATH/TO/Debug/ExampleTests.xctest
print("bundleBeingTested.bundlePath : \(bundleBeingTested.bundlePath)")
// …/PATH/TO/Debug/Example.app
print("bundleMain = " + bundleMain.description) // Xcode Test Agent
print("bundleDoingTest = " + bundleDoingTest.description) // Test Case Bundle
print("bundleUnderTest = " + bundleBeingTested.description) // App Bundle
In Xcode 6|7|8|9, a unit-test bundle path will be in Developer/Xcode/DerivedData
something like ...
/Users/
UserName/
Library/
Developer/
Xcode/
DerivedData/
App-qwertyuiop.../
Build/
Products/
Debug-iphonesimulator/
AppTests.xctest/
foo.txt
... which is separate from the Developer/CoreSimulator/Devices
regular (non-unit-test) bundle path:
/Users/
UserName/
Library/
Developer/
CoreSimulator/
Devices/
_UUID_/
data/
Containers/
Bundle/
Application/
_UUID_/
App.app/
Also note the unit test executable is, by default, linked with the application code. However, the unit test code should only have Target Membership in just the test bundle. The application code should only have Target Membership in the application bundle. At runtime, the unit test target bundle is injected into the application bundle for execution.
Swift Package Manager (SPM) 4:
let testBundle = Bundle(for: type(of: self))
print("testBundle.bundlePath = \(testBundle.bundlePath) ")
Note: By default, the command line swift test
will create a MyProjectPackageTests.xctest
test bundle. And, the swift package generate-xcodeproj
will create a MyProjectTests.xctest
test bundle. These different test bundles have different paths. Also, the different test bundles may have some internal directory structure and content differences.
In either case, the .bundlePath
and .bundleURL
will return the path of test bundle currently being run on macOS. However, Bundle
is not currently implemented for Ubuntu Linux.
Also, command line swift build
and swift test
do not currently provide a mechanism for copying resources.
However, with some effort, it is possible to set up processes for using the Swift Package Manger with resources in the macOS Xcode, macOS command line, and Ubuntu command line environments. One example can be found here: 004.4'2 SW Dev Swift Package Manager (SPM) With Resources Qref
See also: Use resources in unit tests with Swift Package Manager
Swift Package Manager (SwiftPM) 5.3
Swift 5.3 includes Package Manager Resources SE-0271 evolution proposal with "Status: Implemented (Swift 5.3)". :-)
Resources aren't always intended for use by clients of the package; one use of resources might include test fixtures that are only needed by unit tests. Such resources would not be incorporated into clients of the package along with the library code, but would only be used while running the package's tests.
- Add a new
resources
parameter intarget
andtestTarget
APIs to allow declaring resource files explicitly.SwiftPM uses file system conventions for determining the set of source files that belongs to each target in a package: specifically, a target's source files are those that are located underneath the designated "target directory" for the target. By default this is a directory that has the same name as the target and is located in "Sources" (for a regular target) or "Tests" (for a test target), but this location can be customized in the package manifest.
// Get path to DefaultSettings.plist file. let path = Bundle.module.path(forResource: "DefaultSettings", ofType: "plist") // Load an image that can be in an asset archive in a bundle. let image = UIImage(named: "MyIcon", in: Bundle.module, compatibleWith: UITraitCollection(userInterfaceStyle: .dark)) // Find a vertex function in a compiled Metal shader library. let shader = try mtlDevice.makeDefaultLibrary(bundle: Bundle.module).makeFunction(name: "vertexShader") // Load a texture. let texture = MTKTextureLoader(device: mtlDevice).newTexture(name: "Grass", scaleFactor: 1.0, bundle: Bundle.module, options: options)
Example
// swift-tools-version:5.3
import PackageDescription
targets: [
.target(
name: "CLIQuickstartLib",
dependencies: [],
resources: [
// Apply platform-specific rules.
// For example, images might be optimized per specific platform rule.
// If path is a directory, the rule is applied recursively.
// By default, a file will be copied if no rule applies.
.process("Resources"),
]),
.testTarget(
name: "CLIQuickstartLibTests",
dependencies: [],
resources: [
// Copy directories as-is.
// Use to retain directory structure.
// Will be at top level in bundle.
.copy("Resources"),
]),
Current Issue
- Swift 5.3 SPM Resources in tests uses wrong bundle path?
- Swift Package Manager - Resources in test targets
Xcode
Bundle.module
is generated by SwiftPM (see Build/BuildPlan.swift SwiftTargetBuildDescription generateResourceAccessor()) and thus not present in Foundation.Bundle when built by Xcode.
A comparable approach in Xcode would be to manually add a Resources
reference folder to the module, add an Xcode build phase copy
to put the Resource
into some *.bundle
directory, and add a #ifdef Xcode
compiler directive for the Xcode build to work with the resources.
#if Xcode
extension Foundation.Bundle {
/// Returns resource bundle as a `Bundle`.
/// Requires Xcode copy phase to locate files into `*.bundle`
/// or `ExecutableNameTests.bundle` for test resources
static var module: Bundle = {
var thisModuleName = "CLIQuickstartLib"
var url = Bundle.main.bundleURL
for bundle in Bundle.allBundles
where bundle.bundlePath.hasSuffix(".xctest") {
url = bundle.bundleURL.deletingLastPathComponent()
thisModuleName = thisModuleName.appending("Tests")
}
url = url.appendingPathComponent("\(thisModuleName).bundle")
guard let bundle = Bundle(url: url) else {
fatalError("Bundle.module could not load: \(url.path)")
}
return bundle
}()
/// Directory containing resource bundle
static var moduleDir: URL = {
var url = Bundle.main.bundleURL
for bundle in Bundle.allBundles
where bundle.bundlePath.hasSuffix(".xctest") {
// remove 'ExecutableNameTests.xctest' path component
url = bundle.bundleURL.deletingLastPathComponent()
}
return url
}()
}
#endif
With swift Swift 3 the syntax self.dynamicType
has been deprecated, use this instead
let testBundle = Bundle(for: type(of: self))
let fooTxtPath = testBundle.path(forResource: "foo", ofType: "txt")
or
let fooTxtURL = testBundle.url(forResource: "foo", withExtension: "txt")