Java: Fix gradle project root detection

Typical "modern" layout from `gradle init`:

- settings.gradle
- app/build.gradle
- ...

If you open app/src/java/.../Foo.java, we incorrectly pick app/ as the
project root.

Now, when searching for the project root, we continue to search the
varioius file names, but we tag each file name with the "kind" and
keep searching for other files of the same *kind* rather than just the
same name.

Meanwhile, we prefer finding the gradle/maven project. The reason for
this is that jdt.ls spams .project files all over the codebase which
makes any project you've previously opened look like an eclipse project.
This is fine if the project root was previously correctly determined
and/or the projects properly imported, but means that we never
self-correct. So prefer finding the non-native project types so that we
pick the correct root in _most_ cases.

Author: puremourning

ycmd/completers/java/java_completer.py

@@ -22,6 +22,7 @@
 import shutil
 import tempfile
 import threading
+from collections import OrderedDict
 
 from ycmd import responses, utils
 from ycmd.completers.language_server import language_server_completer
@@ -41,12 +42,13 @@
 
 PATH_TO_JAVA = None
 
-PROJECT_FILE_TAILS = [
-  '.project',
-  'pom.xml',
-  'build.gradle',
-  'build.gradle.kts'
-]
+PROJECT_FILE_TAILS = OrderedDict( {
+  'pom.xml': 'maven',
+  'build.gradle': 'gradle',
+  'build.gradle.kts': 'gradle',
+  'settings.gradle': 'gradle',
+  '.project': 'eclipse',
+} )
 
 DEFAULT_WORKSPACE_ROOT_PATH = os.path.abspath( os.path.join(
   os.path.dirname( __file__ ),
@@ -230,19 +232,19 @@ def _LauncherConfiguration( user_options, workspace_root, wipe_config ):
 
 
 def _MakeProjectFilesForPath( path ):
-  for tail in PROJECT_FILE_TAILS:
-    yield os.path.join( path, tail ), tail
+  for tail, type in PROJECT_FILE_TAILS.items():
+    yield os.path.join( path, tail ), tail, type
 
 
 def _FindProjectDir( starting_dir ):
   project_path = starting_dir
   project_type = None
 
   for folder in utils.PathsToAllParentFolders( starting_dir ):
-    for project_file, tail in _MakeProjectFilesForPath( folder ):
+    for project_file, tail, type in _MakeProjectFilesForPath( folder ):
       if os.path.isfile( project_file ):
         project_path = folder
-        project_type = tail
+        project_type = type
         break
     if project_type:
       break
@@ -254,9 +256,14 @@ def _FindProjectDir( starting_dir ):
     LOGGER.debug( 'Found %s style project in %s. Searching for '
                   'project root:', project_type, project_path )
 
+    file_types_to_search_for = [
+      tail for tail, type in PROJECT_FILE_TAILS.items() if type == project_type
+    ]
+
     for folder in utils.PathsToAllParentFolders( os.path.join( project_path,
                                                                '..' ) ):
-      if os.path.isfile( os.path.join( folder, project_type ) ):
+      if any( os.path.isfile( os.path.join( folder, tail ) )
+              for tail in file_types_to_search_for ):
         LOGGER.debug( '  %s is a parent project dir', folder )
         project_path = folder
       else:

ycmd/tests/java/server_management_test.py

@@ -39,8 +39,11 @@
                               StartJavaCompleterServerWithFile )
 from ycmd.tests.test_utils import ( BuildRequest,
                                     CompleterProjectDirectoryMatcher,
+                                    LocationMatcher,
                                     MockProcessTerminationTimingOut,
+                                    RangeMatcher,
                                     TemporaryTestDir,
+                                    WaitForDiagnosticsToBeReady,
                                     WaitUntilCompleterServerReady )
 from ycmd import utils, handlers
 
@@ -296,6 +299,45 @@ def test_ServerManagement_ProjectDetection_MavenParent_Submodule( self, app ):
                  CompleterProjectDirectoryMatcher( project ) )
 
 
+  @TidyJDTProjectFiles( PathToTestFile( 'gradle-init' ) )
+  @IsolatedYcmd()
+  def test_ServerManagement_ProjectDetection_GradleMultipleGradleFiles( self,
+                                                                        app ):
+    testfile = PathToTestFile( 'gradle-init',
+                               'app',
+                               'src',
+                               'main',
+                               'java',
+                               'org',
+                               'example',
+                               'app',
+                               'App.java' )
+    project = PathToTestFile( 'gradle-init' )
+
+    StartJavaCompleterServerWithFile( app, testfile )
+
+    # Run the debug info to check that we have the correct project dir
+    request_data = BuildRequest( filetype = 'java' )
+    assert_that( app.post_json( '/debug_info', request_data ).json,
+                 CompleterProjectDirectoryMatcher( project ) )
+
+    # Check that we successfully actually parse the project too
+    contents = utils.ReadFile( testfile )
+    diags = WaitForDiagnosticsToBeReady( app, testfile, contents, 'java' )
+    assert_that( diags, has_item(
+      has_entries( {
+        'kind': 'WARNING',
+        'text': 'The value of the local variable unused is not used '
+                '[536870973]',
+        'location': LocationMatcher( testfile, 16, 16 ),
+        'location_extent': RangeMatcher( testfile, ( 16, 16 ), ( 16, 22 ) ),
+        'ranges': contains_exactly(
+          RangeMatcher( testfile, ( 16, 16 ), ( 16, 22 ) ) ),
+        'fixit_available': False
+      } ),
+    ) )
+
+
   def test_ServerManagement_ProjectDetection_NoParent( self ):
     with TemporaryTestDir() as tmp_dir:
       with isolated_app() as app:

ycmd/tests/java/testdata/gradle-init/.gitattributes

@@ -0,0 +1,12 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+
+# Binary files should be left untouched
+*.jar           binary
+

ycmd/tests/java/testdata/gradle-init/.gitignore

@@ -0,0 +1,8 @@
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build
+.project
+.classpath
+.settings/

ycmd/tests/java/testdata/gradle-init/app/build.gradle

@@ -0,0 +1,17 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ */
+
+plugins {
+    id 'buildlogic.java-application-conventions'
+}
+
+dependencies {
+    implementation 'org.apache.commons:commons-text'
+    implementation project(':utilities')
+}
+
+application {
+    // Define the main class for the application.
+    mainClass = 'org.example.app.App'
+}

ycmd/tests/java/testdata/gradle-init/app/src/main/java/org/example/app/App.java

@@ -0,0 +1,22 @@
+/*
+ * This source file was generated by the Gradle 'init' task
+ */
+package org.example.app;
+
+import org.example.list.LinkedList;
+
+import static org.example.utilities.StringUtils.join;
+import static org.example.utilities.StringUtils.split;
+import static org.example.app.MessageUtils.getMessage;
+
+import org.apache.commons.text.WordUtils;
+
+public class App {
+    public static void main(String[] args) {
+        String unused;
+        LinkedList tokens;
+        tokens = split(getMessage());
+        String result = join(tokens);
+        System.out.println(WordUtils.capitalize(result));
+    }
+}

ycmd/tests/java/testdata/gradle-init/app/src/main/java/org/example/app/MessageUtils.java

@@ -0,0 +1,10 @@
+/*
+ * This source file was generated by the Gradle 'init' task
+ */
+package org.example.app;
+
+class MessageUtils {
+    public static String getMessage() {
+        return "Hello      World!";
+    }
+}

ycmd/tests/java/testdata/gradle-init/app/src/test/java/org/example/app/MessageUtilsTest.java

@@ -0,0 +1,14 @@
+/*
+ * This source file was generated by the Gradle 'init' task
+ */
+package org.example.app;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class MessageUtilsTest {
+    @Test void testGetMessage() {
+        assertEquals("Hello      World!", MessageUtils.getMessage());
+    }
+}

ycmd/tests/java/testdata/gradle-init/buildSrc/build.gradle

@@ -0,0 +1,13 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ */
+
+plugins {
+    // Support convention plugins written in Groovy. Convention plugins are build scripts in 'src/main' that automatically become available as plugins in the main build.
+    id 'groovy-gradle-plugin'
+}
+
+repositories {
+    // Use the plugin portal to apply community plugins in convention plugins.
+    gradlePluginPortal()
+}

ycmd/tests/java/testdata/gradle-init/buildSrc/settings.gradle

@@ -0,0 +1,14 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * This settings file is used to specify which projects to include in your build-logic build.
+ */
+
+dependencyResolutionManagement {
+    // Reuse version catalog from the main build.
+    versionCatalogs {
+        create('libs', { from(files("../gradle/libs.versions.toml")) })
+    }
+}
+
+rootProject.name = 'buildSrc'