Fix sporadic ConcurrentWeakMapTest failures (Kotlin#2187)

Author: qwwdfsad

kotlinx-coroutines-core/jvm/test/internal/ConcurrentWeakMapTest.kt

@@ -12,8 +12,8 @@ import org.junit.*
 class ConcurrentWeakMapTest : TestBase() {
     @Test
     fun testSimple() {
-        val expect = (1..1000).associateWith { it.toString() }
-        val m = ConcurrentWeakMap<Int, String>()
+        val expect = (1..1000).associate { it.toString().let { it to it } }
+        val m = ConcurrentWeakMap<String, String>()
         // repeat adding/removing a few times
         repeat(5) {
             assertEquals(0, m.size)
@@ -27,7 +27,7 @@ class ConcurrentWeakMapTest : TestBase() {
             assertEquals(expect.keys, m.keys)
             assertEquals(expect.entries, m.entries)
             for ((k, v) in expect) {
-                assertEquals(v, m.get(k))
+                assertEquals(v, m[k])
             }
             assertEquals(expect.size, m.size)
             if (it % 2 == 0) {
@@ -38,9 +38,9 @@ class ConcurrentWeakMapTest : TestBase() {
                 m.clear()
             }
             assertEquals(0, m.size)
-            for ((k, v) in expect) {
-                assertNull(m.get(k))
+            for ((k, _) in expect) {
+                assertNull(m[k])
             }
         }
     }
-}
+}