From 2c70a9dfb1bff8abdf16fa35188d77188931fc3f Mon Sep 17 00:00:00 2001
From: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>
Date: Fri, 5 Feb 2021 17:21:10 +0300
Subject: [PATCH] Test invariant that IDEA evaluator depends on

Fixes #2522
---
 ...jIdeaDebuggerEvaluatorCompatibilityTest.kt | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 kotlinx-coroutines-core/jvm/test/IntellijIdeaDebuggerEvaluatorCompatibilityTest.kt

diff --git a/kotlinx-coroutines-core/jvm/test/IntellijIdeaDebuggerEvaluatorCompatibilityTest.kt b/kotlinx-coroutines-core/jvm/test/IntellijIdeaDebuggerEvaluatorCompatibilityTest.kt
new file mode 100644
index 0000000000..6bbfdd1b4b
--- /dev/null
+++ b/kotlinx-coroutines-core/jvm/test/IntellijIdeaDebuggerEvaluatorCompatibilityTest.kt
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.coroutines
+
+import org.junit.Test
+import kotlin.coroutines.*
+import kotlin.test.*
+
+class IntellijIdeaDebuggerEvaluatorCompatibilityTest {
+
+    /*
+     * This test verifies that our CoroutineScope is accessible to IDEA debugger.
+     *
+     * Consider the following scenario:
+     * ```
+     * runBlocking<Unit> { // this: CoroutineScope
+     *     println("runBlocking")
+     * }
+     * ```
+     * user puts breakpoint to `println` line, opens "Evaluate" window
+     * and executes `launch { println("launch") }`. They (obviously) expect it to work, but
+     * it won't: `{}` in `runBlocking` is `SuspendLambda` and `this` is an unused implicit receiver
+     * that is removed by the compiler (because it's unused).
+     *
+     * But we still want to provide consistent user experience for functions with `CoroutineScope` receiver,
+     * for that IDEA debugger tries to retrieve the scope via `kotlin.coroutines.coroutineContext[Job] as? CoroutineScope`
+     * and with this test we're fixing this behaviour.
+     *
+     * Note that this behaviour is not carved in stone: IDEA fallbacks to `kotlin.coroutines.coroutineContext` for the context if necessary.
+     */
+
+    @Test
+    fun testScopeIsAccessible() = runBlocking<Unit> {
+        verify()
+
+        withContext(Job()) {
+            verify()
+        }
+
+        coroutineScope {
+            verify()
+        }
+
+        supervisorScope {
+            verify()
+        }
+
+    }
+
+    private suspend fun verify() {
+        val ctx = coroutineContext
+        assertTrue { ctx.job is CoroutineScope }
+    }
+}