diff --git a/platform/lang-impl/src/com/intellij/codeInsight/hints/InlayHintsUtils.kt b/platform/lang-impl/src/com/intellij/codeInsight/hints/InlayHintsUtils.kt
index 8e7208119cf2..51cf29f79a91 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/hints/InlayHintsUtils.kt
+++ b/platform/lang-impl/src/com/intellij/codeInsight/hints/InlayHintsUtils.kt
@@ -7,6 +7,7 @@ import com.intellij.configurationStore.deserializeInto
 import com.intellij.configurationStore.serialize
 import com.intellij.lang.Language
 import com.intellij.openapi.actionSystem.AnAction
+import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.application.ReadAction
 import com.intellij.openapi.editor.DefaultLanguageHighlighterColors
 import com.intellij.openapi.editor.Editor
@@ -295,6 +296,7 @@ object InlayHintsUtils {
       }
       else {
         // In tests [computeCodeVision] is executed in sync mode on EDT
+        assert(ApplicationManager.getApplication().isUnitTestMode)
         return ReadAction.compute<CodeVisionState, Throwable> {
           return@compute computable.invoke()
         }