Copy before iterating observables

architecture/src/commonMain/kotlin/observable/Observation.kt

@@ -109,7 +109,8 @@ open class Observation<R : T, T, OO : ObservableOptional<R>>(override val initia
             val result = (v as? ObservableOptional.Value<*>)?.value as R
 
             [email protected] {
-                forEach {
+                // iterate on a copy to prevent concurrent modification
+                toTypedArray().forEach {
                     it(result)
                 }
             }

architecture/src/commonTest/kotlin/observable/ConcurrentModificationTest.kt

@@ -0,0 +1,57 @@
+/*
+ Copyright 2024 Splendo Consulting B.V. The Netherlands
+
+    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
+
+      http://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 com.splendo.kaluga.architecture.observable
+
+import com.splendo.kaluga.base.runBlocking
+import com.splendo.kaluga.test.base.BaseTest
+import kotlinx.coroutines.Dispatchers
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ConcurrentModificationTest : BaseTest() {
+
+    @Test
+    fun testConcurrentModification() = runBlocking(Dispatchers.Main) {
+        val subject = subjectOf(0)
+        var observer3: Disposable? = null
+        var observer2: Disposable? = null
+        var dispose = false
+
+        val observer1 = subject.observe {
+            if (dispose) {
+                observer2!!.dispose()
+            }
+        }
+        observer2 = subject.observe {
+            if (dispose) {
+                observer1.dispose()
+                observer3!!.dispose()
+            }
+        }
+
+        observer3 = subject.observe {
+            // noop
+        }
+
+        dispose = true
+        // due to the weird order of observers disposing each other while they are iterated this will crash if we remove the `toTypedArray()` before `forEach()` in `Observation.kt::setValueUnconfined`
+        subject.post(1)
+
+        assertEquals(1, subject.current)
+    }
+}

resources-compose/src/main/kotlin/KalugaButton.kt

@@ -28,9 +28,7 @@ import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.size
-import androidx.compose.foundation.layout.width
 import androidx.compose.material3.Button
 import androidx.compose.material3.ButtonColors
 import androidx.compose.material3.ButtonDefaults
@@ -41,16 +39,12 @@ import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.Shape
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalLayoutDirection
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.dp
-import androidx.core.content.ContextCompat
-import androidx.core.content.res.ResourcesCompat
 import com.splendo.kaluga.resources.DefaultColors
-import com.splendo.kaluga.resources.KalugaColor
 import com.splendo.kaluga.resources.KalugaImage
 import com.splendo.kaluga.resources.StringStyleAttribute
 import com.splendo.kaluga.resources.StyledStringBuilder
@@ -80,7 +74,9 @@ fun KalugaButton.Composable(modifier: Modifier = Modifier, elevation: ButtonElev
 
     Button(
         action,
-        Modifier.backgroundStyle(stateStyle.backgroundStyle).then(modifier),
+        Modifier
+            .backgroundStyle(stateStyle.backgroundStyle)
+            .then(modifier),
         isEnabled,
         shape = stateStyle.backgroundStyle.shape.shape,
         ButtonColors(Color.Transparent, Color.Transparent, Color.Transparent, Color.Transparent),
@@ -127,14 +123,14 @@ private fun KalugaButtonStyle.WithImageAndText.Composable(modifier: Modifier, is
     val isRightToLeft = LocalLayoutDirection.current == LayoutDirection.Rtl
 
     when (imageGravity) {
-
         ImageGravity.START, ImageGravity.LEFT, ImageGravity.END, ImageGravity.RIGHT ->
             Row(
                 verticalAlignment = Alignment.CenterVertically,
                 horizontalArrangement = Arrangement.spacedBy(spacing.dp),
             ) {
-                if (imageGravity == ImageGravity.START && !isRightToLeft ||
-                    imageGravity == ImageGravity.END && isRightToLeft ||
+                if (
+                    (imageGravity == ImageGravity.START && !isRightToLeft) ||
+                    (imageGravity == ImageGravity.END && isRightToLeft) ||
                     imageGravity == ImageGravity.LEFT
                 ) {
                     imageComposable()

resources-compose/src/main/kotlin/KalugaImage.kt

@@ -71,7 +71,7 @@ fun TintedImage.Composable(
 @Composable
 private fun TintedImagePreview() {
     val image = KalugaImage(AppCompatResources.getDrawable(LocalContext.current, android.R.drawable.ic_media_play)!!).tinted(
-        DefaultColors.blue
+        DefaultColors.blue,
     )
 
     image.Composable(contentDescription = "Play")