Fix Instance

library/process/src/commonMain/kotlin/io/matthewnelson/kmp/process/internal/Instance.kt

@@ -15,15 +15,22 @@
  **/
 package io.matthewnelson.kmp.process.internal
 
-internal class Instance<T: Any?> internal constructor(
-    private val create: () -> T,
-) {
+internal class Instance<T: Any?> internal constructor(create: () -> T) {
 
+    private var create: (() -> T)? = create
     private val instance = SynchronizedSet<T>()
 
     internal fun getOrCreate(): T = instance.withLock {
-        firstOrNull() ?: create()
-            .also { add(it) }
+        if (isEmpty()) {
+            create?.let { function ->
+                function().also { element ->
+                    create = null
+                    add(element)
+                }
+            } ?: throw IllegalStateException()
+        } else {
+            first()
+        }
     }
 
     internal fun getOrNull(): T? = instance.withLock { firstOrNull() }

library/process/src/commonTest/kotlin/io/matthewnelson/kmp/process/ProcessBaseTest.kt

@@ -301,7 +301,7 @@ abstract class ProcessBaseTest {
                 println(stdout.toString())
                 println(stderr.toString())
 
-                p2.waitForAsync(::delay)
+                withContext(Dispatchers.Default) { delay(250.milliseconds) }
 
                 assertEquals(0, p2.stdoutFeedsSize())
                 assertEquals(0, p2.stderrFeedsSize())

library/process/src/commonTest/kotlin/io/matthewnelson/kmp/process/internal/InstanceUnitTest.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2024 Matthew Nelson
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+package io.matthewnelson.kmp.process.internal
+
+import kotlin.test.Test
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+
+class InstanceUnitTest {
+
+    @Test
+    fun givenNullableType_whenGetOrCreate_thenReturnsAsExpected() {
+        val i = Instance<Any?> { Any() }
+
+        assertNull(i.getOrNull())
+        assertNotNull(i.getOrCreate())
+        assertNotNull(i.getOrNull())
+    }
+}