[Gradle, JS] Add test for package.json deserializing

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

@@ -42,9 +42,8 @@ internal class GradleNodeModuleBuilder(
     fun rebuild(): File? {
         if (files.isEmpty()) return null
 
-        val packageJson = srcPackageJsonFile?.reader()?.use {
-            Gson().fromJson(it, PackageJson::class.java)
-        } ?: PackageJson(dependency.moduleName, dependency.moduleVersion)
+        val packageJson = fromSrcPackageJson(srcPackageJsonFile)
+            ?: PackageJson(dependency.moduleName, dependency.moduleVersion)
 
         val jsFiles = files.filter { it.name.endsWith(".js") }
         if (jsFiles.size == 1) {
@@ -65,6 +64,11 @@ internal class GradleNodeModuleBuilder(
     }
 }
 
+internal fun fromSrcPackageJson(packageJson: File?): PackageJson? =
+    packageJson?.reader()?.use {
+        Gson().fromJson(it, PackageJson::class.java)
+    }
+
 private val File.isZip
     get() = isFile && (name.endsWith(".jar") || name.endsWith(".zip"))
 

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/GradleNodeModuleBuilderTest.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.targets.js.npm
+
+import org.junit.Test
+import java.io.File
+import kotlin.test.assertNotNull
+
+class GradleNodeModuleBuilderTest {
+    @Test
+    fun validPackageJsonWithoutDependencies() {
+        val packageJson = fromSrcPackageJson(
+            File("src/test/resources/org/jetbrains/kotlin/gradle/targets/js/npm/GradleNodeModuleBuilderTest/package.json")
+        )
+        assertNotNull(packageJson, "package.json should be deserialized")
+
+        with(packageJson!!) {
+            listOf(
+                dependencies,
+                devDependencies,
+                peerDependencies,
+                optionalDependencies,
+                bundledDependencies
+            ).forEach {
+                assertNotNull(it, "Dependencies should deserialized correctly without null")
+            }
+        }
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/test/resources/org/jetbrains/kotlin/gradle/targets/js/npm/GradleNodeModuleBuilderTest/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "npm",
+  "version": "1.0.0"
+}