Detect missing paths in hg fileview command

If a not existing path is request in the fileview command, it will
be treated as an empty directory. But such a thing does not exist in hg.
Therefore we handle this result as what it is: a not existing path -
and we throw a not found exception.

scm-plugins/scm-hg-plugin/src/main/java/sonia/scm/repository/spi/HgBrowseCommand.java

@@ -36,6 +36,9 @@ import sonia.scm.repository.spi.javahg.HgFileviewCommand;
 
 import java.io.IOException;
 
+import static sonia.scm.ContextEntry.ContextBuilder.entity;
+import static sonia.scm.NotFoundException.notFound;
+
 //~--- JDK imports ------------------------------------------------------------
 
 /**
@@ -93,7 +96,8 @@ public class HgBrowseCommand extends AbstractCommand implements BrowseCommand
     cmd.setLimit(request.getLimit());
     cmd.setOffset(request.getOffset());
 
-    FileObject file = cmd.execute();
+    FileObject file = cmd.execute()
+      .orElseThrow(() -> notFound(entity("File", request.getPath()).in("Revision", revision).in(getRepository())));
     return new BrowserResult(c == null? "tip": c.getNode(), revision, file);
   }
 }

scm-plugins/scm-hg-plugin/src/main/java/sonia/scm/repository/spi/javahg/HgFileviewCommand.java

@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-    
+
 package sonia.scm.repository.spi.javahg;
 
 //~--- non-JDK imports --------------------------------------------------------
@@ -29,12 +29,12 @@ package sonia.scm.repository.spi.javahg;
 import com.aragost.javahg.Repository;
 import com.aragost.javahg.internals.AbstractCommand;
 import com.aragost.javahg.internals.HgInputStream;
-
 import sonia.scm.repository.FileObject;
 
 //~--- JDK imports ------------------------------------------------------------
 
 import java.io.IOException;
+import java.util.Optional;
 
 /**
  * Mercurial command to list files of a repository.
@@ -161,7 +161,7 @@ public class HgFileviewCommand extends AbstractCommand
    *
    * @throws IOException
    */
-  public FileObject execute() throws IOException
+  public Optional<FileObject> execute() throws IOException
   {
     cmdAppend("-t");
 

scm-plugins/scm-hg-plugin/src/main/java/sonia/scm/repository/spi/javahg/HgFileviewCommandResultReader.java

@@ -21,7 +21,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-    
+
 package sonia.scm.repository.spi.javahg;
 
 import com.aragost.javahg.DateTime;
@@ -35,6 +35,10 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Deque;
 import java.util.LinkedList;
+import java.util.Optional;
+
+import static java.util.Optional.empty;
+import static java.util.Optional.of;
 
 class HgFileviewCommandResultReader {
 
@@ -48,7 +52,7 @@ class HgFileviewCommandResultReader {
     this.disableLastCommit = disableLastCommit;
   }
 
-  FileObject parseResult() throws IOException {
+  Optional<FileObject> parseResult() throws IOException {
     Deque<FileObject> stack = new LinkedList<>();
 
     FileObject last = null;
@@ -82,13 +86,17 @@ class HgFileviewCommandResultReader {
 
     if (stack.isEmpty()) {
       // if the stack is empty, the requested path is probably a file
-      return last;
+      return of(last);
+    } else if (stack.size() == 1 && stack.getFirst().isDirectory() && stack.getFirst().getChildren().isEmpty()) {
+      // There are no empty directories in hg. When we get this,
+      // we just get the requested path as a directory, but it does not exist.
+      return empty();
     } else {
       // if the stack is not empty, the requested path is a directory
       if (stream.read() == TRUNCATED_MARK) {
         stack.getLast().setTruncated(true);
       }
-      return stack.getLast();
+      return of(stack.getLast());
     }
   }