lib/swizzle_absolute_xcttestsourcelocation.m

#import <Foundation/Foundation.h>
#import <XCTest/XCTest.h>
#import <objc/runtime.h>

static NSString *kSourceRoot;

NSURL *remapFileUrl(NSURL *fileURL) {
  if ([fileURL.path hasPrefix:kSourceRoot]) {
    return fileURL;
  }

  return [NSURL
      fileURLWithPath:[NSString stringWithFormat:@"%@/%@", kSourceRoot, fileURL.relativePath]];
}

@implementation XCTSourceCodeLocation (FixRelativePaths)

+ (void)load {
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    kSourceRoot = [NSProcessInfo processInfo].environment[@"BUILD_WORKSPACE_DIRECTORY"];
    if (!kSourceRoot) {
      NSLog(@"warning: The 'BUILD_WORKSPACE_DIRECTORY' environment "
             "variable was not set. Test issue navigation might not work.");
      return;
    }
    if (![kSourceRoot hasPrefix:@"/"]) {
      NSLog(@"warning: The 'BUILD_WORKSPACE_DIRECTORY' was not an "
             "absolute path. Test issue navigation might not work.");
      return;
    }

    Class class = [XCTSourceCodeLocation class];

    SEL originalSelector = @selector(initWithFileURL:lineNumber:);
    SEL swizzledSelector = @selector(xxx_initWithRelativeFileURL:lineNumber:);

    Method originalMethod = class_getInstanceMethod(class, originalSelector);
    Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);

    method_exchangeImplementations(originalMethod, swizzledMethod);
  });
}

- (instancetype)xxx_initWithRelativeFileURL:(NSURL *)fileURL lineNumber:(NSInteger)lineNumber {
  // Not recursive because of swizzling
  return [self xxx_initWithRelativeFileURL:remapFileUrl(fileURL) lineNumber:lineNumber];
}

@end