1 files changed, 43 insertions, 0 deletions
diff --git a/android/guava-tests/test/com/google/common/io/FilesCreateTempDirTest.java b/android/guava-tests/test/com/google/common/io/FilesCreateTempDirTest.java
index a31c43770..381eef258 100644
--- a/android/guava-tests/test/com/google/common/io/FilesCreateTempDirTest.java
+++ b/android/guava-tests/test/com/google/common/io/FilesCreateTempDirTest.java
@@ -17,6 +17,7 @@
 package com.google.common.io;
 
 import static com.google.common.base.StandardSystemProperty.JAVA_IO_TMPDIR;
+import static com.google.common.base.StandardSystemProperty.JAVA_SPECIFICATION_VERSION;
 import static com.google.common.base.StandardSystemProperty.OS_NAME;
 import static com.google.common.truth.Truth.assertThat;
 import static java.nio.file.attribute.PosixFilePermission.OWNER_EXECUTE;
@@ -64,6 +65,44 @@ public class FilesCreateTempDirTest extends TestCase {
     }
   }
 
+  public void testBogusSystemPropertiesUsername() {
+    if (isAndroid()) {
+      /*
+       * The test calls directly into the "ACL-based filesystem" code, which isn't available under
+       * old versions of Android. Since Android doesn't use that code path, anyway, there's no need
+       * to test it.
+       */
+      return;
+    }
+
+    /*
+     * Only under Windows (or hypothetically when running with some other non-POSIX, ACL-based
+     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
+     * anything interesting under most environments. Still, we can run it (except for Android, at
+     * least old versions), so we mostly do. This is useful because we don't actually run our CI on
+     * Windows under Java 8, at least as of this writing.
+     *
+     * Under Windows in particular, we want to test that:
+     *
+     * - Under Java 9+, createTempDir() succeeds because it can look up the *real* username, rather
+     * than relying on the one from the system property.
+     *
+     * - Under Java 8, createTempDir() fails because it falls back to the bogus username from the
+     * system property.
+     */
+
+    String save = System.getProperty("user.name");
+    System.setProperty("user.name", "-this-is-definitely-not-the-username-we-are-running-as//?");
+    try {
+      TempFileCreator.testMakingUserPermissionsFromScratch();
+      assertThat(isJava8()).isFalse();
+    } catch (IOException expectedIfJava8) {
+      assertThat(isJava8()).isTrue();
+    } finally {
+      System.setProperty("user.name", save);
+    }
+  }
+
   private static boolean isAndroid() {
     return System.getProperty("java.runtime.name", "").contains("Android");
   }
@@ -71,4 +110,8 @@ public class FilesCreateTempDirTest extends TestCase {
   private static boolean isWindows() {
     return OS_NAME.value().startsWith("Windows");
   }
+
+  private static boolean isJava8() {
+    return JAVA_SPECIFICATION_VERSION.value().equals("1.8");
+  }
 }