bats -c filename prints the number of tests in the file

libexec/bats

@@ -40,14 +40,20 @@ if [ "$1" = "-v" ] || [ "$1" = "--version" ]; then
   exit 0
 fi
 
+count_only=""
+if [ "$1" = "-c" ]; then
+  count_only="-c"
+  shift
+fi
+
 filename="$1"
 if [ -z "$filename" ]; then
   { version
-    echo "usage: $0 <filename>"
+    echo "usage: $0 [-c] <filename>"
   } >&2
   exit 1
 else
   shift
 fi
 
-exec bats-exec "$(expand_path "$filename")" "$@"
+exec bats-exec $count_only "$(expand_path "$filename")" "$@"

libexec/bats-exec

@@ -1,6 +1,12 @@
 #!/usr/bin/env bash
 set -e
 
+BATS_COUNT_ONLY=""
+if [ "$1" = "-c" ]; then
+  BATS_COUNT_ONLY=1
+  shift
+fi
+
 BATS_TEST_FILENAME="$1"
 if [ -z "$BATS_TEST_FILENAME" ]; then
   echo "usage: bats-exec <filename>" >&2
@@ -136,7 +142,12 @@ exec 3<&1
 if [ "$#" -eq 0 ]; then
   bats_preprocess_source
   bats_evaluate_preprocessed_source
-  bats_perform_tests "${BATS_TEST_NAMES[@]}"
+
+  if [ -n "$BATS_COUNT_ONLY" ]; then
+    echo "${#BATS_TEST_NAMES[@]}"
+  else
+    bats_perform_tests "${BATS_TEST_NAMES[@]}"
+  fi
 else
   bats_evaluate_preprocessed_source
   bats_perform_test "$@"

test/bats.bats

@@ -86,3 +86,13 @@ teardown() {
   [ "${lines[5]}" = "    failure stdout 2" ]
   [ "${lines[7]}" = "    failure stderr" ]
 }
+
+@test "-c prints the number of tests" {
+  run bats -c "$FIXTURE_ROOT/empty.bats"
+  [ $status -eq 0 ]
+  [ "$output" = "0" ]
+
+  run bats -c "$FIXTURE_ROOT/output.bats"
+  [ $status -eq 0 ]
+  [ "$output" = "4" ]
+}