Vendoring bats libraries.

Signed-off-by: Chad Metcalf <chad@docker.com>

lib/bats-assert/test/assert_success.bats

@@ -0,0 +1,40 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+@test "assert_success(): returns 0 if \`\$status' is 0" {
+  run true
+  run assert_success
+
+  assert_test_pass
+}
+
+@test "assert_success(): returns 1 and displays details if \`\$status' is not 0" {
+  run bash -c 'echo "a"
+               exit 1'
+  run assert_success
+
+  assert_test_fail <<'ERR_MSG'
+
+-- command failed --
+status : 1
+output : a
+--
+ERR_MSG
+}
+
+@test "assert_success(): displays \`\$output' in multi-line format if it is longer than one line" {
+  run bash -c 'printf "a 0\na 1"
+               exit 1'
+  run assert_success
+
+  assert_test_fail <<'ERR_MSG'
+
+-- command failed --
+status : 1
+output (2 lines):
+  a 0
+  a 1
+--
+ERR_MSG
+}