feat(Maven): Add a function to detect Tycho projects

Tycho [1] is an extension for Maven that supports building artifacts
specific to OSGi and the Eclipse platform. The current Maven package
manager implementation is not able to extract the dependencies of such
projects correctly. Upcoming commits will add a package manager
implementation that can handle such projects. The new function is
going to be used to distinguish between the projects to be handled by
the Maven or the Tycho implementation.

To simplify reusing functionality in tests between these two
package manager implementations, move a helper function to a new test
`Extensions.kt` file.

[1]: https://github.com/eclipse-tycho/tycho

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

Author: oheger-bosch

plugins/package-managers/maven/src/main/kotlin/utils/MavenSupport.kt

@@ -622,6 +622,28 @@ private fun createContainer(): PlexusContainer {
     }
 }
 
+/** The namespace for the Maven Tycho build extension. */
+private const val TYCHO_NAMESPACE = "org.eclipse.tycho"
+
+/** The ID for the Maven Tycho build extension. */
+private const val TYCHO_ID = "tycho-build"
+
+/** The path to the subfolder containing core extensions for Maven. */
+internal const val EXTENSIONS_PATH = ".mvn/extensions.xml"
+
+/**
+ * Return *true* if the given [file] points to a Maven Tycho project. The [file] can either reference the project
+ * folder directly or a file within the project folder.
+ */
+internal fun isTychoProject(file: File): Boolean {
+    val root = file.takeIf { it.isDirectory } ?: file.parentFile
+
+    return root?.resolve(EXTENSIONS_PATH)?.takeIf { it.isFile }?.let { extFile ->
+        val content = extFile.readText()
+        TYCHO_NAMESPACE in content && TYCHO_ID in content
+    } == true
+}
+
 /**
  * Convert this [RemoteRepository] to a repository in the format used by the Maven Repository System.
  * Make sure that all relevant properties are set, especially the proxy and authentication.

plugins/package-managers/maven/src/test/kotlin/Extensions.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2025 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.plugins.packagemanagers.maven
+
+import io.kotest.matchers.shouldBe
+
+import java.io.File
+
+import org.ossreviewtoolkit.plugins.packagemanagers.maven.utils.EXTENSIONS_PATH
+
+/** The content of a Tycho extension file. */
+private const val TYCHO_EXTENSION_XML = """
+<extensions>
+  <extension>
+    <groupId>org.eclipse.tycho</groupId>
+    <artifactId>tycho-build</artifactId>
+    <version>4.0.0</version>
+  </extension>
+</extensions>
+"""
+
+/**
+ * Add the required structures to this [File] to make it a Tycho project. Write the given [content] in the extensions
+ * file.
+ */
+internal fun File.addTychoExtension(content: String = TYCHO_EXTENSION_XML) =
+    with(resolve(EXTENSIONS_PATH)) {
+        parentFile.mkdirs() shouldBe true
+        writeText(content)
+    }

plugins/package-managers/maven/src/test/kotlin/utils/MavenSupportTest.kt

@@ -20,6 +20,7 @@
 package org.ossreviewtoolkit.plugins.packagemanagers.maven.utils
 
 import io.kotest.core.spec.style.WordSpec
+import io.kotest.engine.spec.tempdir
 import io.kotest.matchers.shouldBe
 
 import io.mockk.every
@@ -38,6 +39,8 @@ import org.eclipse.aether.repository.Proxy
 import org.eclipse.aether.repository.RemoteRepository
 import org.eclipse.aether.util.repository.AuthenticationBuilder
 
+import org.ossreviewtoolkit.plugins.packagemanagers.maven.addTychoExtension
+
 class MavenSupportTest : WordSpec({
     @Suppress("DEPRECATION") // For deprecated ArtifactRepository interface.
     "toArtifactRepository()" should {
@@ -156,4 +159,53 @@ class MavenSupportTest : WordSpec({
             }
         }
     }
+
+    "isTychoProject()" should {
+        "return true if the Tycho extension is found" {
+            val projectDir = tempdir()
+            projectDir.addTychoExtension()
+
+            isTychoProject(projectDir) shouldBe true
+        }
+
+        "return false if the extension file does not contain the Tycho extension" {
+            val projectDir = tempdir()
+            projectDir.addTychoExtension(
+                """
+                <extensions>
+                    <extension>
+                        <groupId>org.eclipse.tycho</groupId>
+                        <artifactId>tycho-foo</artifactId>
+                        <version>4.0.0</version>
+                    </extension>
+                </extensions>
+                """.trimIndent()
+            )
+
+            isTychoProject(projectDir) shouldBe false
+        }
+
+        "return false if there is no extension file" {
+            val projectDir = tempdir()
+            val mvnDir = projectDir.resolve(".mvn")
+            mvnDir.mkdirs()
+
+            isTychoProject(projectDir) shouldBe false
+        }
+
+        "return false if there is no .mvn directory" {
+            val projectDir = tempdir()
+
+            isTychoProject(projectDir) shouldBe false
+        }
+
+        "return true for a pom file in a folder that has the Tycho extension" {
+            val projectDir = tempdir()
+            projectDir.addTychoExtension()
+
+            val pomFile = projectDir.resolve("pom.xml")
+
+            isTychoProject(pomFile) shouldBe true
+        }
+    }
 })