Improve testing for deleteTree and deleteTreesBelow.

Add missing tests for the deleteTreesBelow entry point (expecting to leave
the given path untouched) and for corner cases like handling an unwritable
directory.

Addresses #7527.

RELNOTES: None.
PiperOrigin-RevId: 239489795

src/test/java/com/google/devtools/build/lib/vfs/FileSystemTest.java

@@ -803,7 +803,7 @@ public void testDeleteNonEmptyDirectoryNotDeletedFile() throws Exception {
   }
 
   @Test
-  public void testDeleteTreeCommandDeletesTree() throws IOException {
+  public void testDeleteTreeDeletesContents() throws IOException {
     Path topDir = absolutize("top-dir");
     Path file1 = absolutize("top-dir/file-1");
     Path file2 = absolutize("top-dir/file-2");
@@ -818,9 +818,7 @@ public void testDeleteTreeCommandDeletesTree() throws IOException {
     FileSystemUtils.createEmptyFile(file3);
     FileSystemUtils.createEmptyFile(file4);
 
-    Path toDelete = topDir;
-    toDelete.deleteTree();
-
+    topDir.deleteTree();
     assertThat(file4.exists()).isTrue();
     assertThat(topDir.exists()).isFalse();
     assertThat(file1.exists()).isFalse();
@@ -830,57 +828,120 @@ public void testDeleteTreeCommandDeletesTree() throws IOException {
   }
 
   @Test
-  public void testDeleteTreeCommandsDeletesUnreadableDirectories() throws IOException {
+  public void testDeleteTreeDeletesUnreadableDirectories() throws IOException {
     Path topDir = absolutize("top-dir");
     Path aDir = absolutize("top-dir/a-dir");
+    Path file1 = absolutize("top-dir/a-dir/file1");
+    Path file2 = absolutize("top-dir/a-dir/file2");
 
     topDir.createDirectory();
     aDir.createDirectory();
-
-    Path toDelete = topDir;
+    FileSystemUtils.createEmptyFile(file1);
+    FileSystemUtils.createEmptyFile(file2);
 
     try {
       aDir.setReadable(false);
+      aDir.setExecutable(false);
     } catch (UnsupportedOperationException e) {
-      // For file systems that do not support setting readable attribute to
-      // false, this test is simply skipped.
-
+      // Skip testing if the file system does not support clearing the needed attibutes.
       return;
     }
 
-    toDelete.deleteTree();
+    topDir.deleteTree();
     assertThat(topDir.exists()).isFalse();
     assertThat(aDir.exists()).isFalse();
+    assertThat(file1.exists()).isFalse();
+    assertThat(file2.exists()).isFalse();
   }
 
   @Test
-  public void testDeleteTreeCommandDoesNotFollowLinksOut() throws IOException {
+  public void testDeleteTreeDeletesUnwritableDirectories() throws IOException {
     Path topDir = absolutize("top-dir");
-    Path file1 = absolutize("top-dir/file-1");
-    Path file2 = absolutize("top-dir/file-2");
     Path aDir = absolutize("top-dir/a-dir");
-    Path file3 = absolutize("top-dir/a-dir/file-3");
-    Path file4 = absolutize("file-4");
+    Path file1 = absolutize("top-dir/a-dir/file1");
+    Path file2 = absolutize("top-dir/a-dir/file2");
 
     topDir.createDirectory();
+    aDir.createDirectory();
     FileSystemUtils.createEmptyFile(file1);
     FileSystemUtils.createEmptyFile(file2);
-    aDir.createDirectory();
-    FileSystemUtils.createEmptyFile(file3);
-    FileSystemUtils.createEmptyFile(file4);
 
-    Path toDelete = topDir;
-    Path outboundLink = absolutize("top-dir/outbound-link");
-    outboundLink.createSymbolicLink(file4);
-
-    toDelete.deleteTree();
+    try {
+      aDir.setWritable(false);
+    } catch (UnsupportedOperationException e) {
+      // Skip testing if the file system does not support clearing the needed attibutes.
+      return;
+    }
 
-    assertThat(file4.exists()).isTrue();
+    topDir.deleteTree();
     assertThat(topDir.exists()).isFalse();
+    assertThat(aDir.exists()).isFalse();
     assertThat(file1.exists()).isFalse();
     assertThat(file2.exists()).isFalse();
-    assertThat(aDir.exists()).isFalse();
-    assertThat(file3.exists()).isFalse();
+  }
+
+  @Test
+  public void testDeleteTreeDoesNotFollowInnerLinks() throws IOException {
+    Path topDir = absolutize("top-dir");
+    Path file = absolutize("file");
+    Path outboundLink = absolutize("top-dir/outbound-link");
+
+    topDir.createDirectory();
+    FileSystemUtils.createEmptyFile(file);
+    outboundLink.createSymbolicLink(file);
+
+    topDir.deleteTree();
+    assertThat(file.exists()).isTrue();
+    assertThat(topDir.exists()).isFalse();
+  }
+
+  @Test
+  public void testDeleteTreeDoesNotFollowTopLink() throws IOException {
+    Path topDir = absolutize("top-dir");
+    Path file = absolutize("file");
+
+    FileSystemUtils.createEmptyFile(file);
+    topDir.createSymbolicLink(file);
+
+    topDir.deleteTree();
+    assertThat(file.exists()).isTrue();
+    assertThat(topDir.exists()).isFalse();
+  }
+
+  @Test
+  public void testTreesDeletesBelowDeletesContentsOnly() throws IOException {
+    Path topDir = absolutize("top-dir");
+    Path file = absolutize("top-dir/file");
+    Path subdir = absolutize("top-dir/subdir");
+
+    topDir.createDirectory();
+    FileSystemUtils.createEmptyFile(file);
+    subdir.createDirectory();
+
+    topDir.deleteTreesBelow();
+    assertThat(topDir.exists()).isTrue();
+    assertThat(file.exists()).isFalse();
+    assertThat(subdir.exists()).isFalse();
+  }
+
+  @Test
+  public void testTreesDeletesBelowIgnoresMissingTopDir() throws IOException {
+    Path topDir = absolutize("top-dir");
+
+    assertThat(topDir.exists()).isFalse();
+    topDir.deleteTreesBelow(); // Expect no exception.
+    assertThat(topDir.exists()).isFalse();
+  }
+
+  @Test
+  public void testTreesDeletesBelowIgnoresNonDirectories() throws IOException {
+    Path topFile = absolutize("top-file");
+
+    FileSystemUtils.createEmptyFile(topFile);
+
+    assertThat(topFile.exists()).isTrue();
+    topFile.deleteTreesBelow(); // Expect no exception.
+    assertThat(topFile.exists()).isTrue();
   }
 
   // Test the date functions