I'm trying to use the --experimental-event-stream-output to get events about testing, like the following.
swift test \
--experimental-event-stream-output <path> \
--experimental-event-stream-version <ABI-version>
I noticed that if a test crashes, e.g. because of index out of bound, assert, fatalError, ..., the last event for the crashed test will always be runStarted, as if the test never ends.
For example, given tests
import Testing
@Test func `array access crash`() {
let array = [UInt8]()
#expect(array[0] == 0)
}
@Test func `fatal error crash`() {
fatalError("This is a fatal error crash test.")
}
The even stream will be
{
"kind": "test",
"payload": {
"displayName": "array access crash",
"id": "SimpleTestCrashTests.`array access crash`()\/SimpleTestCrashTests.swift:3:2",
"isParameterized": false,
"kind": "function",
"name": "`array access crash`()",
"sourceLocation": {
"_filePath": "\/SimpleTestCrash\/Tests\/SimpleTestCrashTests\/SimpleTestCrashTests.swift",
"column": 2,
"fileID": "SimpleTestCrashTests\/SimpleTestCrashTests.swift",
"line": 3
}
},
"version": 0
}
{
"kind": "test",
"payload": {
"displayName": "fatal error crash",
"id": "SimpleTestCrashTests.`fatal error crash`()\/SimpleTestCrashTests.swift:8:2",
"isParameterized": false,
"kind": "function",
"name": "`fatal error crash`()",
"sourceLocation": {
"_filePath": "\/SimpleTestCrash\/Tests\/SimpleTestCrashTests\/SimpleTestCrashTests.swift",
"column": 2,
"fileID": "SimpleTestCrashTests\/SimpleTestCrashTests.swift",
"line": 8
}
},
"version": 0
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 376990.417884416,
"since1970": 1774627675.367574
},
"kind": "runStarted",
"messages": [
{
"symbol": "default",
"text": "Test run started."
},
{
"symbol": "details",
"text": "Testing Library Version: 6.3 (980fec0f03c56f7)"
},
{
"symbol": "details",
"text": "Target Platform: arm64-apple-macosx"
}
]
},
"version": 0
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 376990.418342375,
"since1970": 1774627675.368032
},
"kind": "testStarted",
"messages": [
{
"symbol": "default",
"text": "Test \"fatal error crash\" started."
}
],
"testID": "SimpleTestCrashTests.`fatal error crash`()\/SimpleTestCrashTests.swift:8:2"
},
"version": 0
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 376990.418342333,
"since1970": 1774627675.368032
},
"kind": "testStarted",
"messages": [
{
"symbol": "default",
"text": "Test \"array access crash\" started."
}
],
"testID": "SimpleTestCrashTests.`array access crash`()\/SimpleTestCrashTests.swift:3:2"
},
"version": 0
}
I would expect to receive issueRecorded, testEnded, and runEnded like regular failed tests, like
import Testing
@Test func `failed test`() {
#expect(false)
}
which issues the following events
{
"kind": "test",
"payload": {
"displayName": "failed test",
"id": "SimpleTestSomeFailedTests.`failed test`()\/SimpleTestSomeFailedTests.swift:3:2",
"isParameterized": false,
"kind": "function",
"name": "`failed test`()",
"sourceLocation": {
"_filePath": "\/Users\/flicker_soul\/Documents\/Developer\/swift\/SwiftDocTest\/Tests\/DocTestRunnerTests\/Props\/SimpleTestSomeFailed\/Tests\/SimpleTestSomeFailedTests\/SimpleTestSomeFailedTests.swift",
"column": 2,
"fileID": "SimpleTestSomeFailedTests\/SimpleTestSomeFailedTests.swift",
"filePath": "\/Users\/flicker_soul\/Documents\/Developer\/swift\/SwiftDocTest\/Tests\/DocTestRunnerTests\/Props\/SimpleTestSomeFailed\/Tests\/SimpleTestSomeFailedTests\/SimpleTestSomeFailedTests.swift",
"line": 3
}
},
"version": "6.3.0"
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 378958.348472375,
"since1970": 1774629643.307811
},
"kind": "runStarted",
"messages": [
{
"symbol": "default",
"text": "Test run started."
},
{
"symbol": "details",
"text": "Testing Library Version: 6.3 (980fec0f03c56f7)"
},
{
"symbol": "details",
"text": "Target Platform: arm64-apple-macosx"
}
]
},
"version": "6.3.0"
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 378958.348759333,
"since1970": 1774629643.308098
},
"kind": "testStarted",
"messages": [
{
"symbol": "default",
"text": "Test \"failed test\" started."
}
],
"testID": "SimpleTestSomeFailedTests.`failed test`()\/SimpleTestSomeFailedTests.swift:3:2"
},
"version": "6.3.0"
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 378958.349141833,
"since1970": 1774629643.30848
},
"issue": {
"isFailure": true,
"isKnown": false,
"severity": "error",
"sourceLocation": {
"_filePath": "\/Users\/flicker_soul\/Documents\/Developer\/swift\/SwiftDocTest\/Tests\/DocTestRunnerTests\/Props\/SimpleTestSomeFailed\/Tests\/SimpleTestSomeFailedTests\/SimpleTestSomeFailedTests.swift",
"column": 5,
"fileID": "SimpleTestSomeFailedTests\/SimpleTestSomeFailedTests.swift",
"filePath": "\/Users\/flicker_soul\/Documents\/Developer\/swift\/SwiftDocTest\/Tests\/DocTestRunnerTests\/Props\/SimpleTestSomeFailed\/Tests\/SimpleTestSomeFailedTests\/SimpleTestSomeFailedTests.swift",
"line": 4
}
},
"kind": "issueRecorded",
"messages": [
{
"symbol": "fail",
"text": "Expectation failed: false"
}
],
"testID": "SimpleTestSomeFailedTests.`failed test`()\/SimpleTestSomeFailedTests.swift:3:2"
},
"version": "6.3.0"
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 378958.349297041,
"since1970": 1774629643.308635
},
"kind": "testEnded",
"messages": [
{
"symbol": "fail",
"text": "Test \"failed test\" failed after 0.001 seconds with 1 issue."
}
],
"testID": "SimpleTestSomeFailedTests.`failed test`()\/SimpleTestSomeFailedTests.swift:3:2"
},
"version": "6.3.0"
}
{
"kind": "event",
"payload": {
"instant": {
"absolute": 378958.349480958,
"since1970": 1774629643.308819
},
"kind": "runEnded",
"messages": [
{
"symbol": "fail",
"text": "Test run with 1 test in 0 suites failed after 0.001 seconds with 1 issue."
}
]
},
"version": "6.3.0"
}
Is this a design choice or a bug in the library? 
I found a potential related issue Crashing tests result in empty xunit output with Swift Testing · Issue #1110 · swiftlang/swift-testing · GitHub , which seems to suggest this behavior is not expected.