feat(Yarn): Add basic support for Corepack [1].

According to the Yarn 2+ documentation, Corepack is the preferred way
to install this package manager. If this method is used, the name of
the executable has to be determined differently.

[1]: https://yarnpkg.com/corepack

Signed-off-by: Oliver Heger <oliver.heger@bosch.io>

analyzer/src/funTest/kotlin/Yarn2Test.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2024 The ORT Project Authors (see <https://github.com/oss-review-toolkit/ort/blob/main/NOTICE>)
+ *
+ * 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
+ *
+ *     https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * License-Filename: LICENSE
+ */
+
+package org.ossreviewtoolkit.analyzer
+
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.core.spec.style.WordSpec
+import io.kotest.engine.spec.tempdir
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.string.shouldContain
+
+import org.ossreviewtoolkit.model.config.AnalyzerConfiguration
+import org.ossreviewtoolkit.model.config.PackageManagerConfiguration
+import org.ossreviewtoolkit.model.config.RepositoryConfiguration
+import org.ossreviewtoolkit.plugins.packagemanagers.node.Yarn2
+
+class Yarn2Test : WordSpec({
+    "command" should {
+        "return the executable defined in yarnrc.yml" {
+            val workingDir = tempdir()
+            val executable = "yarn-wrapper.js"
+            workingDir.resolve(".yarnrc.yml").writeText("yarnPath: $executable")
+            val executableFile = workingDir.resolve(executable).also {
+                it.writeText("#!/usr/bin/env node\nconsole.log('yarn')")
+            }
+
+            val yarn = Yarn2("yarn", workingDir, AnalyzerConfiguration(), RepositoryConfiguration())
+            val command = yarn.command(workingDir)
+
+            command shouldBe executableFile.absolutePath
+        }
+
+        "throw if no executable is defined in yarnrc.yml" {
+            val workingDir = tempdir()
+            workingDir.resolve(".yarnrc.yml").writeText("someProperty: some-value")
+
+            val yarn = Yarn2("yarn", workingDir, AnalyzerConfiguration(), RepositoryConfiguration())
+
+            val exception = shouldThrow<IllegalArgumentException> {
+                yarn.command(workingDir)
+            }
+
+            exception.localizedMessage shouldContain "No Yarn 2+ executable"
+        }
+
+        "throw if the executable defined in yarnrc.yml does not exist" {
+            val workingDir = tempdir()
+            val executable = "non-existing-yarn-wrapper.js"
+            workingDir.resolve(".yarnrc.yml").writeText("yarnPath: $executable")
+
+            val yarn = Yarn2("yarn", workingDir, AnalyzerConfiguration(), RepositoryConfiguration())
+
+            val exception = shouldThrow<IllegalArgumentException> {
+                yarn.command(workingDir)
+            }
+
+            exception.localizedMessage shouldContain executable
+        }
+
+        "return the default executable name if corepack is enabled" {
+            val workingDir = tempdir()
+            val yarn2Options = mapOf("corepackEnabled" to "true")
+            val analyzerConfiguration = AnalyzerConfiguration(
+                packageManagers = mapOf("Yarn2" to PackageManagerConfiguration(options = yarn2Options))
+            )
+
+            val yarn = Yarn2("Yarn2", workingDir, analyzerConfiguration, RepositoryConfiguration())
+            val command = yarn.command(workingDir)
+
+            command shouldBe "yarn"
+        }
+    }
+})

plugins/package-managers/node/src/main/kotlin/Yarn2.kt

@@ -87,6 +87,9 @@ private enum class YarnDependencyType(val type: String) {
  * - *disableRegistryCertificateVerification*: If true, the `yarn npm info` commands called by this package manager will
  *   not verify the server certificate of the HTTPS connection to the NPM registry. This allows to replace the latter by
  *   a local one, e.g. for intercepting the requests or replaying them.
+ * - *corepackEnabled*: If true, this implementation assumes that Yarn has been installed via
+ *   [Corepack](https://yarnpkg.com/corepack). In this case, the default executable name is used, which points to a
+ *   binary proxy that is able to download and install the correct version of Yarn.
  */
 class Yarn2(
     name: String,
@@ -100,6 +103,11 @@ class Yarn2(
          */
         const val OPTION_DISABLE_REGISTRY_CERTIFICATE_VERIFICATION = "disableRegistryCertificateVerification"
 
+        /**
+         * The name of the option that determines whether Yarn 2+ was installed via Corepack.
+         */
+        const val OPTION_COREPACK_ENABLED = "corepackEnabled"
+
         /**
          * The name of Yarn 2+ resource file.
          */
@@ -119,6 +127,11 @@ class Yarn2(
          * The amount of package details to query at once with `yarn npm info`.
          */
         private const val BULK_DETAILS_SIZE = 1000
+
+        /**
+         * The name of the default executable. This is used when the [OPTION_COREPACK_ENABLED] option is set.
+         */
+        private const val DEFAULT_EXECUTABLE_NAME = "yarn"
     }
 
     class Factory : AbstractPackageManagerFactory<Yarn2>("Yarn2") {
@@ -135,7 +148,8 @@ class Yarn2(
      * The Yarn 2+ executable is not installed globally: The program shipped by the project in `.yarn/releases` is used
      * instead. The value of the 'yarnPath' property in the resource file `.yarnrc.yml` defines the path to the
      * executable for the current project e.g. `yarnPath: .yarn/releases/yarn-3.2.1.cjs`.
-     * This map holds the mapping between the directory and their Yarn 2+ executables.
+     * This map holds the mapping between the directory and their Yarn 2+ executables. It is only used if Yarn has not
+     * been installed via Corepack; then it is accessed under a default name.
      */
     private val yarn2ExecutablesByPath: MutableMap<File, String> = mutableMapOf()
 
@@ -157,6 +171,8 @@ class Yarn2(
     override fun command(workingDir: File?): String {
         if (workingDir == null) return ""
 
+        if (options[OPTION_COREPACK_ENABLED].toBoolean()) return DEFAULT_EXECUTABLE_NAME
+
         return yarn2ExecutablesByPath.getOrPut(workingDir) {
             val yarnConfig = yamlMapper.readTree(workingDir.resolve(YARN2_RESOURCE_FILE))
             val yarnCommand = requireNotNull(yarnConfig[YARN_PATH_PROPERTY_NAME]) {