Add test for ruby-build definitions

test/definitions.bats

+#!/usr/bin/env bats
+
+load test_helper
+NUM_DEFINITIONS="$(ls "$BATS_TEST_DIRNAME"/../share/ruby-build | wc -l)"
+
+@test "list built-in definitions" {
+  run ruby-build --definitions
+  assert_success
+  assert_output_contains "1.9.3-p194"
+  assert_output_contains "jruby-1.7.9"
+  assert [ "${#lines[*]}" -eq "$NUM_DEFINITIONS" ]
+}
+
+@test "installing nonexistent definition" {
+  run ruby-build "nonexistent" "${TMP}/install"
+  assert [ "$status" -eq 2 ]
+  assert_output "ruby-build: definition not found: nonexistent"
+}