From c8867dcb77aa43c7199912c713a29b950cad4eaf Mon Sep 17 00:00:00 2001
From: Pawel Krolikowski <pawel@uber.com>
Date: Fri, 19 Jul 2019 01:15:44 +0200
Subject: [PATCH 1/2] Add a better version of join.

Skips empty arguments.
Handles defaults.
Has tests.
---
 bash.sh      | 30 +++++++++++++++++++++++-----
 test-bash.sh | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+), 5 deletions(-)

diff --git a/bash.sh b/bash.sh
index 907b628..efa446c 100755
--- a/bash.sh
+++ b/bash.sh
@@ -53,14 +53,34 @@ array_filter() {
 #
 # Join array elements with a string.
 #
-# $1: String separator
-# $@: Array elements
+# $1: String default, used in case array is empty
+# $2: String separator, has to be a single element
+# $@: Array elements, empty elements will be skipped
 #
-array_join() {
-    local sep=$1; shift
-    IFS=$sep eval 'echo "$*"'
+
+join() {
+    local -a args
+    local default
+    local ifs
+    local IFS
+
+    default="$1"; shift
+
+    ifs="$1"; shift
+
+    [ "${#ifs}" -gt 1 ] && exit 1
+
+    # read into array, ifs is still a space
+    read -r -a args <<< "$*"
+
+    IFS="$ifs"
+    # args will be unbound if no more arguments were passed in
+    # check for that, use default if necessary
+    # otherwise dump the string with overwritten ifs
+    [ -z "${args-}" ] && echo "$default" || echo "${args[*]}"
 }
 
+
 ################
 # Benchmarking #
 ################
diff --git a/test-bash.sh b/test-bash.sh
index dfe5633..05d5737 100755
--- a/test-bash.sh
+++ b/test-bash.sh
@@ -44,6 +44,62 @@ test_resolve_symlinks() {
     [ "$(resolve_symlinks /tmp/1/2/foo)" == "/tmp/foo" ]
 }
 
+test_join_standard() {
+    local result
+
+    result=$(join "def" - 1 2 3)
+
+    [ "$result" == "1-2-3" ]
+}
+
+test_join_one() {
+    local result
+
+    result=$(join "def" - 1)
+
+    [ "$result" == "1" ]
+}
+
+test_join_spaces() {
+    local result
+
+    result=$(join "def" - 1 '' '' 3)
+
+    [ "$result" == "1-3" ]
+}
+
+test_join_more_spaces() {
+    local result
+
+    result=$(join "def" - 1   3)
+
+    [ "$result" == "1-3" ]
+}
+
+test_join_other_delimeter() {
+    local result
+
+    result=$(join "def" "b" 1   3)
+
+    [ "$result" == "1b3" ]
+}
+
+test_join_invalid_delimeter() {
+    local result
+
+    result=$(join "def" "bb" 1   3)
+
+    [ "$?" == 1 ]
+}
+
+test_join_default() {
+    local result
+
+    result=$(join "def" - '' '')
+
+    [ "$result" == "def" ]
+}
+
 tests() {
     local ret=0
     local test_log="/tmp/${0##*/}.test.log"

From e496e63992da460ba36afa636a98a36c9cfaf0b7 Mon Sep 17 00:00:00 2001
From: Pawel Krolikowski <pawel@uber.com>
Date: Fri, 19 Jul 2019 01:19:45 +0200
Subject: [PATCH 2/2] more tests

---
 bash.sh      | 2 +-
 test-bash.sh | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/bash.sh b/bash.sh
index efa446c..3d33bc8 100755
--- a/bash.sh
+++ b/bash.sh
@@ -53,7 +53,7 @@ array_filter() {
 #
 # Join array elements with a string.
 #
-# $1: String default, used in case array is empty
+# $1: String default, used in case array to join is empty
 # $2: String separator, has to be a single element
 # $@: Array elements, empty elements will be skipped
 #
diff --git a/test-bash.sh b/test-bash.sh
index 05d5737..b29301d 100755
--- a/test-bash.sh
+++ b/test-bash.sh
@@ -92,6 +92,14 @@ test_join_invalid_delimeter() {
     [ "$?" == 1 ]
 }
 
+test_join_no_delimeter() {
+    local result
+
+    result=$(join "def")
+
+    [ "$result" == "def" ]
+}
+
 test_join_default() {
     local result