2 files changed, 13 insertions, 2 deletions
diff --git a/bin/uid-zero b/bin/uid-zero
index 2976cbb..9b2640f 100755
--- a/bin/uid-zero
+++ b/bin/uid-zero
@@ -1,7 +1,9 @@
 #!/bin/bash
 
+FILE=${1:-'/etc/passwd'}
+
 if [[ "$OSTYPE" == "darwin"* ]]; then
-  cat /etc/passwd | cut -d: -f1,3 | grep ':0'
+  cat $FILE | cut -d: -f1,3 | grep ':0'
 else
-  cat /etc/passwd | grep -P '^\w+:[x]:\d+:0.*$'
+  cat $FILE | grep -P '^\w+:[x]:\d+:0.*$'
 fi
diff --git a/test/uid_zero_test.bats b/test/uid_zero_test.bats
new file mode 100644
index 0000000..397312e
--- /dev/null
+++ b/test/uid_zero_test.bats
@@ -0,0 +1,9 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+@test "it finds the user with uid 0" {
+  run ./bin/uid-zero test/fixtures/passwd
+
+  assert_success $'root:0'
+}