diff --git a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/mocha/KotlinMocha.kt b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/mocha/KotlinMocha.kt
index df60c46bfb5..44175ac5fe4 100644
--- a/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/mocha/KotlinMocha.kt
+++ b/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/testing/mocha/KotlinMocha.kt
@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.gradle.targets.js.npm.npmProject
 import org.jetbrains.kotlin.gradle.targets.js.testing.KotlinJsTest
 import org.jetbrains.kotlin.gradle.targets.js.testing.KotlinJsTestFramework
 import org.jetbrains.kotlin.gradle.targets.js.testing.KotlinTestRunnerCliArgs
+import java.io.File
 
 class KotlinMocha(override val compilation: KotlinJsCompilation) : KotlinJsTestFramework {
     private val project: Project = compilation.target.project
@@ -59,19 +60,31 @@ class KotlinMocha(override val compilation: KotlinJsCompilation) : KotlinJsTestF
             exclude = task.excludePatterns
         )
 
-        createAdapterJs(task)
-
         val mocha = npmProject.require("mocha/bin/mocha")
-        val adapter = npmProject.require("./$ADAPTER_NODEJS")
+
+        val file = task.nodeModulesToLoad
+            .map { npmProject.require(it) }
+            .single()
+
+        val adapter = createAdapterJs(file, debug)
 
         val args = mutableListOf(
             "--require",
             npmProject.require("source-map-support/register.js")
-
         ).apply {
+            if (debug) {
+                // Idle run of tests to load file with source maps to enable break points
+                add("--require")
+                add(
+                    npmProject.require("kotlin-test-js-runner/kotlin-test-nodejs-idle-runner.js")
+                )
+                add("--require")
+                add(file)
+
+                add("--inspect-brk")
+            }
             add(mocha)
-            addAll(cliArg("--inspect-brk", debug))
-            add(adapter)
+            add(adapter.canonicalPath)
             addAll(cliArgs.toList())
             addAll(cliArg("--reporter", "kotlin-test-js-runner/mocha-kotlin-reporter.js"))
             addAll(cliArg("--timeout", timeout))
@@ -85,27 +98,33 @@ class KotlinMocha(override val compilation: KotlinJsCompilation) : KotlinJsTestF
         )
     }
 
-    private fun cliArg(cli: String, value: Boolean): List<String> {
-        return if (value) listOf(cli) else emptyList()
-    }
-
     private fun cliArg(cli: String, value: String?): List<String> {
         return value?.let { listOf(cli, it) } ?: emptyList()
     }
 
-    private fun createAdapterJs(task: KotlinJsTest) {
+    private fun createAdapterJs(
+        file: String,
+        debug: Boolean
+    ): File {
         val npmProject = compilation.npmProject
-        val file = task.nodeModulesToLoad
-            .map { npmProject.require(it) }
-            .single()
 
         val adapterJs = npmProject.dir.resolve(ADAPTER_NODEJS)
         adapterJs.printWriter().use { writer ->
             val adapter = npmProject.require("kotlin-test-js-runner/kotlin-test-nodejs-runner.js")
+            val escapedFile = file.jsQuoted()
+
+            if (debug) {
+                // Invalidate caches after idle run
+                writer.println("delete require.cache[require.resolve($escapedFile)]")
+                writer.println("delete require.cache[require.resolve('kotlin-test')]")
+            }
+
             writer.println("require(${adapter.jsQuoted()})")
 
-            writer.println("module.exports = require(${file.jsQuoted()})")
+            writer.println("module.exports = require($escapedFile)")
         }
+
+        return adapterJs
     }
 
     companion object {
diff --git a/libraries/tools/kotlin-test-js-runner/build.gradle.kts b/libraries/tools/kotlin-test-js-runner/build.gradle.kts
index e4518f67863..48a27ebe27d 100644
--- a/libraries/tools/kotlin-test-js-runner/build.gradle.kts
+++ b/libraries/tools/kotlin-test-js-runner/build.gradle.kts
@@ -51,6 +51,7 @@ tasks {
         inputs.dir("src")
         inputs.files(
             "nodejs.ts",
+            "nodejs-idle.ts",
             "karma.ts",
             "karma-kotlin-reporter.js",
             "karma-debug-runner.js",
diff --git a/libraries/tools/kotlin-test-js-runner/nodejs-idle.ts b/libraries/tools/kotlin-test-js-runner/nodejs-idle.ts
new file mode 100755
index 00000000000..5d4a45fbe62
--- /dev/null
+++ b/libraries/tools/kotlin-test-js-runner/nodejs-idle.ts
@@ -0,0 +1,15 @@
+import {KotlinTestRunner} from "./src/KotlinTestRunner";
+
+const kotlin_test = require('kotlin-test');
+
+const nothingTest: KotlinTestRunner = {
+    suite(name: string, isIgnored: boolean, fn: () => void): void {
+        console.error("suite", name)
+    },
+    test(name: string, isIgnored: boolean, fn: () => void): void {
+        console.error("test", name)
+
+    }
+};
+
+kotlin_test.setAdapter(nothingTest);
\ No newline at end of file
diff --git a/libraries/tools/kotlin-test-js-runner/rollup.config.js b/libraries/tools/kotlin-test-js-runner/rollup.config.js
index b0e8871231e..ddde86ca9ce 100644
--- a/libraries/tools/kotlin-test-js-runner/rollup.config.js
+++ b/libraries/tools/kotlin-test-js-runner/rollup.config.js
@@ -16,6 +16,16 @@ export default [
         },
         plugins: plugins()
     },
+    {
+        input: './nodejs-idle.ts',
+        output: {
+            file: 'lib/kotlin-test-nodejs-idle-runner.js',
+            format: 'cjs',
+            banner: '#!/usr/bin/env node',
+            sourcemap: true
+        },
+        plugins: plugins()
+    },
     {
         input: './karma.ts',
         output: {