Add tests

Author: dkhalanskyjb

kotlinx-coroutines-test/common/test/Helpers.kt

@@ -31,9 +31,32 @@ inline fun <T> assertRunsFast(timeout: Duration, block: () -> T): T {
 inline fun <T> assertRunsFast(block: () -> T): T = assertRunsFast(2.seconds, block)
 
 /**
- * Passes [test] as an argument to [block], but as a function returning not a [TestResult] but [Unit].
+ * Runs [test], and then invokes [block], passing to it the lambda that functionally behaves
+ * the same way [test] does.
 */
-expect fun testResultMap(block: (() -> Unit) -> Unit, test: () -> TestResult): TestResult
+fun testResultMap(block: (() -> Unit) -> Unit, test: () -> TestResult): TestResult = testResultChain(
+    block = test,
+    after = {
+        block { it.getOrThrow() }
+        createTestResult { }
+    }
+)
+
+/**
+ * Chains together [block] and [after], passing the result of [block] to [after].
+ */
+expect fun testResultChain(block: () -> TestResult, after: (Result<Unit>) -> TestResult): TestResult
+
+fun testResultChain(vararg chained: (Result<Unit>) -> TestResult): TestResult =
+    if (chained.isEmpty()) {
+        createTestResult { }
+    } else {
+        testResultChain(block = {
+            chained[0](Result.success(Unit))
+        }) {
+            testResultChain(*chained.drop(1).toTypedArray())
+        }
+    }
 
 class TestException(message: String? = null): Exception(message)
 

kotlinx-coroutines-test/common/test/TestScopeTest.kt

@@ -489,6 +489,61 @@ class TestScopeTest {
         } catch (e: TimeoutCancellationException) {
             assertContains(e.message!!, "virtual")
         }
+
+    /*
+     * Tests that the [TestScope] exception reporting mechanism will report the exceptions that happen between
+     * different tests.
+     *
+     * This test must be ran manually, because such exceptions still go through the global exception handler
+     * (as there's no guarantee that another test will happen), and the global exception handler will
+     * log the exceptions or, on Native, crash the test suite.
+     */
+    @Test
+    @Ignore
+    fun testReportingStrayUncaughtExceptionsBetweenTests() {
+        val thrown = TestException("x")
+        testResultChain({
+            // register a handler for uncaught exceptions
+            runTest { }
+        }, {
+            GlobalScope.launch(start = CoroutineStart.UNDISPATCHED) {
+                throw thrown
+            }
+            runTest {
+                fail("unreached")
+            }
+        }, {
+            // this `runTest` will not report the exception
+            runTest {
+                when (val exception = it.exceptionOrNull()) {
+                    is UncaughtExceptionsBeforeTest -> {
+                        assertEquals(1, exception.suppressedExceptions.size)
+                        assertSame(exception.suppressedExceptions[0], thrown)
+                    }
+                    else -> fail("unexpected exception: $exception")
+                }
+            }
+        })
+    }
+
+    /**
+     * Tests that the uncaught exceptions that happen during the test are reported.
+     */
+    @Test
+    fun testReportingStrayUncaughtExceptionsDuringTest(): TestResult {
+        val thrown = TestException("x")
+        return testResultChain({ _ ->
+            runTest {
+                val job = launch(Dispatchers.Default + NonCancellable) {
+                    throw thrown
+                }
+                job.join()
+            }
+        }, {
+            runTest {
+                assertEquals(thrown, it.exceptionOrNull())
+            }
+        })
     }
 
     companion object {

kotlinx-coroutines-test/js/test/Helpers.kt

@@ -1,20 +1,17 @@
 /*
- * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2016-2022 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package kotlinx.coroutines.test
 
 import kotlin.test.*
 
-actual fun testResultMap(block: (() -> Unit) -> Unit, test: () -> TestResult): TestResult =
-    test().then(
+actual fun testResultChain(block: () -> TestResult, after: (Result<Unit>) -> TestResult): TestResult =
+    block().then(
         {
-            block {
-            }
+            after(Result.success(Unit))
         }, {
-            block {
-                throw it
-            }
+            after(Result.failure(it))
         })
 
 actual typealias NoJs = Ignore

kotlinx-coroutines-test/jvm/test/HelpersJvm.kt

@@ -3,8 +3,11 @@
  */
 package kotlinx.coroutines.test
 
-actual fun testResultMap(block: (() -> Unit) -> Unit, test: () -> TestResult) {
-    block {
-        test()
+actual fun testResultChain(block: () -> TestResult, after: (Result<Unit>) -> TestResult): TestResult {
+    try {
+        block()
+        after(Result.success(Unit))
+    } catch (e: Throwable) {
+        after(Result.failure(e))
     }
 }

kotlinx-coroutines-test/native/test/Helpers.kt

@@ -5,9 +5,12 @@ package kotlinx.coroutines.test
 
 import kotlin.test.*
 
-actual fun testResultMap(block: (() -> Unit) -> Unit, test: () -> TestResult) {
-    block {
-        test()
+actual fun testResultChain(block: () -> TestResult, after: (Result<Unit>) -> TestResult): TestResult {
+    try {
+        block()
+        after(Result.success(Unit))
+    } catch (e: Throwable) {
+        after(Result.failure(e))
     }
 }