Make task to fetch an empty file

Now that Jermolene/TiddlyWiki5#5455 is
merged we can use a standard empty file.

Makefile

@@ -51,6 +51,20 @@ bundle-install:
 secrets:
 	-docker-compose run --rm --no-deps base bash -c "EDITOR=vi bin/rails credentials:edit"
 
+# Currently we need the prerelease, later we'll switch to stable versions
+EMPTY_URL=https://tiddlywiki.com/prerelease/empty.html
+EMPTY_TARGET=rails/empties/tw5.html
+$(EMPTY_TARGET):
+	curl -s $(EMPTY_URL) -o $(EMPTY_TARGET)
+	@echo Fetched version: $$(grep '<meta name="tiddlywiki-version"' rails/empties/tw5.html  | cut -d\" -f4)
+
+empty: $(EMPTY_TARGET)
+
+clear-empty:
+	@rm -f $(EMPTY_TARGET)
+
+update-empty: clear-empty empty
+
 # Try to be smart about how to run the tests
 # TODO: Refactor and integrate with "shell" and "join"
 tests:

README.md

@@ -41,8 +41,9 @@ Install all ruby gems, node modules, and initialize the databases:
 
     make rails-init
 
-Add a TW empty file to rails/empties/tw5.html. (For best results it needs to
-be slightly modified. Todo: Explain how to get the modifications.)
+Fetch an empty TW file:
+
+    make empty
 
 Run the test suite: