From 93d3cec96f25ce6171ff25b3c70a0a083712ce13 Mon Sep 17 00:00:00 2001
From: Mike Bland <mbland@acm.org>
Date: Tue, 14 Feb 2017 16:37:35 -0500
Subject: [PATCH] exec-test: Use printf -v in bats_frame_* functions

This is part of the effort to improve performance by reducing the number
of command substitutions/subshells spawned by `bats_debug_trap`.

Under Bash 3.2.57(1)-release on a MacBook Pro with a 2.9GHz Intel Core
i5 CPU and 8GB 1867MHz DDR3 RAM, this makes `bin/bats test/` go from:

  44 tests, 0 failures

  real    0m7.565s
  user    0m3.664s
  sys     0m3.368s

to:

  real    0m6.449s
  user    0m3.290s
  sys     0m2.665s
---
 libexec/bats-exec-test | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/libexec/bats-exec-test b/libexec/bats-exec-test
index 518c116..734f874 100755
--- a/libexec/bats-exec-test
+++ b/libexec/bats-exec-test
@@ -114,18 +114,21 @@ bats_capture_stack_trace() {
     fi
   done
 
-  BATS_SOURCE="$(bats_frame_filename "${BATS_CURRENT_STACK_TRACE[0]}")"
-  BATS_LINENO="$(bats_frame_lineno "${BATS_CURRENT_STACK_TRACE[0]}")"
+  bats_frame_filename "${BATS_CURRENT_STACK_TRACE[0]}" 'BATS_SOURCE'
+  bats_frame_lineno "${BATS_CURRENT_STACK_TRACE[0]}" 'BATS_LINENO'
 }
 
 bats_print_stack_trace() {
   local frame
   local index=1
   local count="${#@}"
+  local filename
+  local lineno
 
   for frame in "$@"; do
-    local filename="$(bats_trim_filename "$(bats_frame_filename "$frame")")"
-    local lineno="$(bats_frame_lineno "$frame")"
+    bats_frame_filename "$frame" 'filename'
+    filename="$(bats_trim_filename "$filename")"
+    bats_frame_lineno "$frame" 'lineno'
 
     if [ $index -eq 1 ]; then
       echo -n "# ("
@@ -133,7 +136,8 @@ bats_print_stack_trace() {
       echo -n "#  "
     fi
 
-    local fn="$(bats_frame_function "$frame")"
+    local fn
+    bats_frame_function "$frame" 'fn'
     if [ "$fn" != "$BATS_TEST_NAME" ]; then
       echo -n "from function \`$fn' "
     fi
@@ -151,8 +155,11 @@ bats_print_stack_trace() {
 bats_print_failed_command() {
   local frame="$1"
   local status="$2"
-  local filename="$(bats_frame_filename "$frame")"
-  local lineno="$(bats_frame_lineno "$frame")"
+  local filename
+  local lineno
+
+  bats_frame_filename "$frame" 'filename'
+  bats_frame_lineno "$frame" 'lineno'
 
   local failed_line="$(bats_extract_line "$filename" "$lineno")"
   local failed_command="$(bats_strip_string "$failed_line")"
@@ -166,12 +173,12 @@ bats_print_failed_command() {
 }
 
 bats_frame_lineno() {
-  printf '%s\n' "${1%% *}"
+  printf -v "$2" '%s' "${1%% *}"
 }
 
 bats_frame_function() {
   local __bff_function="${1#* }"
-  printf '%s\n' "${__bff_function%% *}"
+  printf -v "$2" '%s' "${__bff_function%% *}"
 }
 
 bats_frame_filename() {
@@ -181,7 +188,7 @@ bats_frame_filename() {
   if [ "$__bff_filename" = "$BATS_TEST_SOURCE" ]; then
     __bff_filename="$BATS_TEST_FILENAME"
   fi
-  printf '%s\n' "$__bff_filename"
+  printf -v "$2" '%s' "$__bff_filename"
 }
 
 bats_extract_line() {