[Gradle, JS] KT-37207 Add test on file-only dependency

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/Kotlin2JsGradlePluginIT.kt

@@ -543,6 +543,7 @@ abstract class AbstractKotlin2JsGradlePluginIT(private val irBackend: Boolean) :
         build("build") {
             assertSuccessful()
             assertFileExists("build/js/node_modules/file-dependency")
+            assertFileExists("build/js/node_modules/file-dependency-2")
         }
     }
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/npm-dependencies/build.gradle.kts

@@ -17,6 +17,7 @@ kotlin.sourceSets {
             // It has transitive dependency on custom github version of escodegen
             implementation(npm("@yworks/optimizer", "1.0.6"))
             implementation(npm("file-dependency", projectDir.resolve("file-dependency")))
+            implementation(npm(projectDir.resolve("file-dependency-2")))
         }
     }
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/npm-dependencies/file-dependency-2/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "file-dependency-2",
+  "version": "1.0.0",
+  "main": "index.js",
+  "private": true
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/NpmDependency.kt

@@ -133,7 +133,7 @@ internal fun fileVersion(directory: File): String =
 internal fun moduleName(directory: File): String {
     val packageJson = directory.resolve(PACKAGE_JSON)
 
-    check(!packageJson.isFile) {
+    check(packageJson.isFile) {
         "There is no NPM module in $directory. Declare valid $PACKAGE_JSON in it."
     }