Unit tests should not store data in the .lemminx folder under the user's home directory.

[fbricon]

Unit tests currently write data in ~/.lemminx, this is wrong:

[INFO] Running XML Validation Command Test
2022-07-29 10:22:14.995:INFO::main: Logging initialized @19707ms to org.eclipse.jetty.util.log.StdErrLog
2022-07-29 10:22:15.094:INFO:oejs.Server:main: jetty-9.4.41.v20210516; built: 2021-05-16T23:56:28.993Z; git: 98607f93c7833e7dc59489b13f3cb0a114fb9f4c; jvm 17.0.1+12
2022-07-29 10:22:15.146:INFO:oejs.AbstractConnector:main: Started ServerConnector@7c40ffef{HTTP/1.1, (http/1.1)}{0.0.0.0:55113}
2022-07-29 10:22:15.146:INFO:oejs.Server:main: Started @19858ms
Jul 29, 2022 10:22:15 AM org.eclipse.lemminx.uriresolver.FileServer start
INFO: http server started on port 55113
Jul 29, 2022 10:22:15 AM org.eclipse.lemminx.uriresolver.FileServer getUri
INFO: remote uri : http://localhost:55113/tag.xsd
Jul 29, 2022 10:22:15 AM org.eclipse.lemminx.uriresolver.FileServer getUri
INFO: remote uri : http://localhost:55113/tag.dtd
Jul 29, 2022 10:22:15 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloading http://localhost:55113/tag.xsd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.xsd...
Jul 29, 2022 10:22:15 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloaded http://localhost:55113/tag.xsd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.xsd in 111ms
Jul 29, 2022 10:22:17 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloading http://localhost:55113/tag.dtd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.dtd...
Jul 29, 2022 10:22:17 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloaded http://localhost:55113/tag.dtd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.dtd in 4ms
Jul 29, 2022 10:22:21 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloading http://localhost:55113/tag.dtd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.dtd...
Jul 29, 2022 10:22:21 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloading http://localhost:55113/tag.xsd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.xsd...
Jul 29, 2022 10:22:21 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloaded http://localhost:55113/tag.dtd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.dtd in 3ms
Jul 29, 2022 10:22:21 AM org.eclipse.lemminx.uriresolver.CacheResourcesManager lambda$downloadResource$0
INFO: Downloaded http://localhost:55113/tag.xsd to /Users/fbricon/.lemminx/cache/http/localhost/55113/tag.xsd in 3ms
2022-07-29 10:22:22.373:INFO:oejs.AbstractConnector:main: Stopped ServerConnector@7c40ffef{HTTP/1.1, (http/1.1)}{0.0.0.0:0}
2022-07-29 10:22:22.375:INFO:oejs.Server:main: jetty-9.4.41.v20210516; built: 2021-05-16T23:56:28.993Z; git: 98607f93c7833e7dc59489b13f3cb0a114fb9f4c; jvm 17.0.1+12
2022-07-29 10:22:22.377:INFO:oejs.AbstractConnector:main: Started ServerConnector@5d05f453{HTTP/1.1, (http/1.1)}{0.0.0.0:55126}
2022-07-29 10:22:22.377:INFO:oejs.Server:main: Started @27089ms
Jul 29, 2022 10:22:22 AM org.eclipse.lemminx.uriresolver.FileServer start

Tests should use a clean cache directory, that would not pollute the user cache and also ensure idempotency

[angelozerr]

+1

[rgrunber]

It's difficult to know which tests may trigger the downloading behaviour, so the only way to be safe is to ensure all test suites use a different cache.

Easiest way is probably something like :

diff --git a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/AbstractCacheBasedTest.java b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/AbstractCacheBasedTest.java
index 51a4cf22..97fdd6c3 100644
--- a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/AbstractCacheBasedTest.java
+++ b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/AbstractCacheBasedTest.java
@@ -21,6 +21,7 @@ import com.google.common.io.RecursiveDeleteOption;
 import org.eclipse.lemminx.utils.FilesUtils;
 import org.eclipse.lemminx.utils.ProjectUtils;
 import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
 
 /**
@@ -33,7 +34,6 @@ public abstract class AbstractCacheBasedTest {
 	@BeforeEach
 	public final void setupCache() throws Exception {
 		clearCache();
-		System.setProperty(FilesUtils.LEMMINX_WORKDIR_KEY, TEST_WORK_DIRECTORY.toAbsolutePath().toString());
 	}
 
 	@AfterEach
@@ -41,7 +41,6 @@ public abstract class AbstractCacheBasedTest {
 		if (Files.exists(TEST_WORK_DIRECTORY)) {
 			MoreFiles.deleteDirectoryContents(TEST_WORK_DIRECTORY,RecursiveDeleteOption.ALLOW_INSECURE);
 		}
-		System.clearProperty(FilesUtils.LEMMINX_WORKDIR_KEY);
 		FilesUtils.resetDeployPath();
 	}
 }
\ No newline at end of file
diff --git a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/utils/FilesUtilsTest.java b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/utils/FilesUtilsTest.java
index 86dcb797..12154179 100644
--- a/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/utils/FilesUtilsTest.java
+++ b/org.eclipse.lemminx/src/test/java/org/eclipse/lemminx/utils/FilesUtilsTest.java
@@ -31,6 +31,7 @@ public class FilesUtilsTest {
 
 	@Test
 	public void testFilesCachePathPreference() throws Exception {
+		String origWorkDir = System.getProperty(FilesUtils.LEMMINX_WORKDIR_KEY);
 		System.clearProperty(FilesUtils.LEMMINX_WORKDIR_KEY);
 		String newBasePathString = System.getProperty("user.home");
 		String newSubPathString = Paths.get("New", "Sub", "Path").toString();
@@ -38,6 +39,7 @@ public class FilesUtilsTest {
 		FilesUtils.setCachePathSetting(newBasePathString);
 		Path finalPath = FilesUtils.getDeployedPath(newSubPath);
 		assertEquals(Paths.get(newBasePathString, newSubPathString).toString(), finalPath.toString());
+		System.setProperty(FilesUtils.LEMMINX_WORKDIR_KEY, origWorkDir);
 	}
 
 	@Test
diff --git a/pom.xml b/pom.xml
index 2410dd21..72c7eabb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -133,6 +133,7 @@
 					<version>3.0.0-M4</version>
 					<configuration>
 						<runOrder>random</runOrder>
+						<argLine>-Dlemminx.workdir=${project.build.directory}/test-cache/</argLine>
 						<statelessTestsetReporter implementation="org.apache.maven.plugin.surefire.extensions.junit5.JUnit5Xml30StatelessReporter">
 							<disable>false</disable>
 							<usePhrasedFileName>false</usePhrasedFileName>

The problem is those running the tests through an IDE (eg. Eclipse) would also need to make sure that property is set in the test launch configuration.