upgrade to modern bats

Author: paulirish

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "test/test_helper/bats-assert"]
 	path = test/test_helper/bats-assert
 	url = https://github.com/ztombol/bats-assert
+[submodule "test/bats"]
+	path = test/bats
+	url = https://github.com/bats-core/bats-core.git

hacking-and-testing.md

@@ -14,23 +14,25 @@ cd ~/projects/catfabulator && git diff
 
 ### Running tests
 
-You'll need to install [bats](https://github.com/sstephenson/bats#installing-bats-from-source), the Bash automated testing system. It's also available as `brew install bats`
+The tests use [bats-core](https://bats-core.readthedocs.io/en/latest/index.html), the Bash automated testing system.
 
 ```sh
 git submodule sync
-git submodule update --init # pull in the assertion library, bats-assert
+git submodule update --init
 
 # run the test suite once:
-bats test
+./test/bats/bin/bats test
 
 # run it on every change with `entr`
 brew install entr
-ls --color=never diff-so-fancy test/*.bats | entr bats test
+ls --color=never diff-so-fancy test/*.bats | entr ./test/bats/bin/bats test
 ```
+
 When writing assertions, you'll likely want to compare to expected output. To grab that reliably, you can use something like `git --no-pager diff | diff-so-fancy > output.txt`
 
 You can lint your scripts via shellcheck, our CI bots will also check.
 
 ```sh
 brew install shellcheck
 shellcheck *.sh
+```

package.json

@@ -6,7 +6,7 @@
     "diff-so-fancy": "diff-so-fancy"
   },
   "scripts": {
-    "test": "bats test"
+    "test": "./test/bats/bin/bats test"
   },
   "repository": {
     "type": "git",

test/bats

@@ -11,7 +11,7 @@ output=$( load_fixture "ls-function" | $diff_so_fancy )
 
 @test "diff-so-fancy runs exits without error" {
 	load_fixture "ls-function" | $diff_so_fancy
-	assert_success
+	run assert_success
 }
 
 @test "index line is removed entirely" {