StdlibUnittest: ask the child process to terminate, and check its termination status

If a child process crashes outside of a test context, the parent process
should signal test failure. This behavior is a sign of something bad
happening in the child (for example, memory corruption), and should not
go unnoticed.

Author: gribozavr

stdlib/private/StdlibUnittest/StdlibUnittest.swift.gyb

@@ -645,6 +645,12 @@ func _childProcess() {
 
   while let line = _stdlib_getline() {
     let parts = line._split(separator: ";")
+
+    if parts[0] == _stdlibUnittestStreamPrefix {
+      precondition(parts[1] == "shutdown")
+      return
+    }
+
     let testSuiteName = parts[0]
     let testName = parts[1]
     var testParameter: Int?
@@ -865,6 +871,42 @@ struct _ParentProcess {
       capturedCrashStdout, capturedCrashStderr)
   }
 
+  internal mutating func _shutdownChild() -> (failed: Bool, Void) {
+    if _pid == nil {
+      // The child process is not running.  Report that it didn't fail during
+      // shutdown.
+      return (failed: false, ())
+    }
+    print("\(_stdlibUnittestStreamPrefix);shutdown", to: &_childStdin)
+
+    var childCrashed = false
+
+    func processLine(_ line: String, isStdout: Bool) -> (done: Bool, Void) {
+      if isStdout {
+        print("stdout>>> \(line)")
+      } else {
+        if findSubstring(line, _crashedPrefix) != nil {
+          childCrashed = true
+        }
+        print("stderr>>> \(line)")
+      }
+      return (done: false, ())
+    }
+
+    _readFromChild(
+      onStdoutLine: { processLine($0, isStdout: true) },
+      onStderrLine: { processLine($0, isStdout: false) })
+
+    let status = _waitForChild()
+    switch status {
+    case .exit(0):
+      return (failed: childCrashed, ())
+    default:
+      print("Abnormal child process termination: \(status).")
+      return (failed: true, ())
+    }
+  }
+
   internal enum _TestStatus {
     case skip([TestRunPredicate])
     case pass
@@ -1024,6 +1066,11 @@ struct _ParentProcess {
         print("\(testSuite.name): All tests passed")
       }
     }
+    let (failed: failedOnShutdown, ()) = _shutdownChild()
+    if failedOnShutdown {
+      print("The child process failed during shutdown, aborting.")
+      _testSuiteFailedCallback()
+    }
   }
 }
 

validation-test/StdlibUnittest/ChildProcessShutdown/FailIfChildCrashesDuringShutdown.swift

@@ -0,0 +1,35 @@
+// RUN: %target-run-simple-swift 2>&1 | FileCheck %s
+// REQUIRES: executable_test
+
+import StdlibUnittest
+#if os(Linux)
+import Glibc
+#else
+import Darwin
+#endif
+
+_setTestSuiteFailedCallback() { print("abort()") }
+
+//
+// Test that harness aborts when a test crashes if a child process crashes
+// after all tests have finished running.
+//
+
+var TestSuiteChildCrashes = TestSuite("TestSuiteChildCrashes")
+
+TestSuiteChildCrashes.test("passes") {
+  atexit {
+    fatalError("crash at exit")
+  }
+}
+
+// CHECK: [ RUN      ] TestSuiteChildCrashes.passes
+// CHECK: [       OK ] TestSuiteChildCrashes.passes
+// CHECK: TestSuiteChildCrashes: All tests passed
+// CHECK: stderr>>> fatal error: crash at exit:
+// CHECK: stderr>>> CRASHED: SIG
+// CHECK: The child process failed during shutdown, aborting.
+// CHECK: abort()
+
+runAllTests()
+

validation-test/StdlibUnittest/ChildProcessShutdown/FailIfChildExitsDuringShutdown.swift

@@ -0,0 +1,34 @@
+// RUN: %target-run-simple-swift 2>&1 | FileCheck %s
+// REQUIRES: executable_test
+
+import StdlibUnittest
+#if os(Linux)
+import Glibc
+#else
+import Darwin
+#endif
+
+_setTestSuiteFailedCallback() { print("abort()") }
+
+//
+// Test that harness aborts when a test crashes if a child process exits with a
+// non-zero code after all tests have finished running.
+//
+
+var TestSuiteChildExits = TestSuite("TestSuiteChildExits")
+
+TestSuiteChildExits.test("passes") {
+  atexit {
+    _exit(1)
+  }
+}
+
+// CHECK: [ RUN      ] TestSuiteChildExits.passes
+// CHECK: [       OK ] TestSuiteChildExits.passes
+// CHECK: TestSuiteChildExits: All tests passed
+// CHECK: Abnormal child process termination: Exit(1).
+// CHECK: The child process failed during shutdown, aborting.
+// CHECK: abort()
+
+runAllTests()
+

validation-test/StdlibUnittest/ChildProcessShutdown/PassIfChildCrashedDuringTestExecution.swift

@@ -0,0 +1,24 @@
+// RUN: %target-run-simple-swift
+// REQUIRES: executable_test
+
+import StdlibUnittest
+#if os(Linux)
+import Glibc
+#else
+import Darwin
+#endif
+
+//
+// Test that harness correctly handles the case when there is no child process
+// to terminate during shutdown because it crashed during test execution.
+//
+
+var TestSuiteChildCrashes = TestSuite("TestSuiteChildCrashes")
+
+TestSuiteChildCrashes.test("passes") {
+  expectCrashLater()
+  fatalError("crash")
+}
+
+runAllTests()
+