Make deleting a non-existent file is tolerable

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApi.java

@@ -92,9 +92,13 @@ interface MailboxApi {
 	 * Used by owner and contacts to delete files.
 	 * <p>
 	 * Returns 200 OK (no exception) if deletion was successful.
+	 *
+	 * @throws TolerableFailureException on 404 response,
+	 * because file was most likely deleted already.
 	 */
 	void deleteFile(MailboxProperties properties, String folderId,
-			String fileId) throws IOException, ApiException;
+			String fileId)
+			throws IOException, ApiException, TolerableFailureException;
 
 	/**
 	 * Lists all contact outboxes that have files available

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApiImpl.java

@@ -223,7 +223,8 @@ class MailboxApiImpl implements MailboxApi {
 
 	@Override
 	public void deleteFile(MailboxProperties properties, String folderId,
-			String fileId) throws IOException, ApiException {
+			String fileId)
+			throws IOException, ApiException, TolerableFailureException {
 		String path = "/files/" + folderId + "/" + fileId;
 		Request request = getRequestBuilder(properties.getAuthToken())
 				.delete()
@@ -231,6 +232,7 @@ class MailboxApiImpl implements MailboxApi {
 				.build();
 		OkHttpClient client = httpClientProvider.get();
 		Response response = client.newCall(request).execute();
+		if (response.code() == 404) throw new TolerableFailureException();
 		if (response.code() != 200) throw new ApiException();
 	}
 

bramble-core/src/test/java/org/briarproject/bramble/mailbox/MailboxApiTest.java

@@ -591,6 +591,7 @@ public class MailboxApiTest extends BrambleTestCase {
 		server.enqueue(new MockResponse());
 		server.enqueue(new MockResponse().setResponseCode(205));
 		server.enqueue(new MockResponse().setResponseCode(401));
+		server.enqueue(new MockResponse().setResponseCode(404));
 		server.start();
 		String baseUrl = getBaseUrl(server);
 		MailboxProperties properties =
@@ -621,6 +622,15 @@ public class MailboxApiTest extends BrambleTestCase {
 		assertEquals("/files/" + contactInboxId + "/" + name,
 				request3.getPath());
 		assertToken(request3, token);
+
+		// file not found is tolerable
+		assertThrows(TolerableFailureException.class, () ->
+				api.deleteFile(properties, contactInboxId, name));
+		RecordedRequest request4 = server.takeRequest();
+		assertEquals("DELETE", request4.getMethod());
+		assertEquals("/files/" + contactInboxId + "/" + name,
+				request4.getPath());
+		assertToken(request4, token);
 	}
 
 	@Test

bramble-core/src/test/java/org/briarproject/bramble/mailbox/MailboxIntegrationTest.java

@@ -225,6 +225,10 @@ public class MailboxIntegrationTest extends BrambleTestCase {
 				api.getFiles(ownerProperties, contact.outboxId));
 		assertEquals(emptyList(), api.getFolders(ownerProperties));
 
+		// deleting a non-existent file is tolerable
+		assertThrows(TolerableFailureException.class, () ->
+				api.deleteFile(ownerProperties, contact.outboxId, file3name));
+
 		// owner deletes contact again to leave clean state for other tests
 		api.deleteContact(ownerProperties, contactId);
 		assertEquals(emptyList(), api.getContacts(ownerProperties));