Add bad command line option errors

libexec/bats

@@ -6,7 +6,9 @@ version() {
 }
 
 usage() {
+  local errmsg="$1"
   version
+  [ -n "$errmsg" ] && echo "Error: $errmsg"
   echo "Usage: bats [-c] [-p | -t] <test> [<test> ...]"
 }
 
@@ -100,14 +102,14 @@ for option in "${options[@]}"; do
     pretty="1"
     ;;
   * )
-    usage >&2
+    usage "Bad command line option '-$option'" >&2
     exit 1
     ;;
   esac
 done
 
 if [ "${#arguments[@]}" -eq 0 ]; then
-  usage >&2
+  usage "Must specify at least one <test>" >&2
   exit 1
 fi
 

libexec/bats-exec-test

@@ -17,7 +17,7 @@ fi
 
 BATS_TEST_FILENAME="$1"
 if [ -z "$BATS_TEST_FILENAME" ]; then
-  echo "usage: bats-exec <filename>" >&2
+  echo "usage: bats-exec-test <filename>" >&2
   exit 1
 elif [ ! -f "$BATS_TEST_FILENAME" ]; then
   echo "bats: $BATS_TEST_FILENAME does not exist" >&2

test/bats.bats

@@ -3,10 +3,18 @@
 load test_helper
 fixtures bats
 
-@test "no arguments prints usage instructions" {
+@test "no arguments prints message and usage instructions" {
   run bats
   [ $status -eq 1 ]
-  [ $(expr "${lines[1]}" : "Usage:") -ne 0 ]
+  [ $(expr "${lines[1]}" : "Error: Must specify at least one") -ne 0 ]
+  [ $(expr "${lines[2]}" : "Usage:") -ne 0 ]
+}
+
+@test "invalid option prints message and usage instructions" {
+  run bats --invalid-option
+  [ $status -eq 1 ]
+  [ $(expr "${lines[1]}" : "Error: Bad command line option") -ne 0 ]
+  [ $(expr "${lines[2]}" : "Usage:") -ne 0 ]
 }
 
 @test "-v and --version print version number" {