Configure travis to test with multiple bash versions

.travis.yml

@@ -1,5 +1,6 @@
 language: c
-script: bin/bats --tap test
+script:
+  ./test-with-all-bashes.sh
 notifications:
   email:
     on_success: never

README.md

@@ -30,6 +30,7 @@ Bash's `errexit` (`set -e`) option when running test cases. If every
 command in the test case exits with a `0` status code (success), the
 test passes. In this way, each line is an assertion of truth.
 
+Bats supports Bash version 3.1 and later.
 
 ## Running tests
 

libexec/bats

@@ -116,11 +116,11 @@ for filename in "${arguments[@]}"; do
   if [ -d "$filename" ]; then
     shopt -s nullglob
     for suite_filename in "$(expand_path "$filename")"/*.bats; do
-      filenames["${#filenames[@]}"]="$suite_filename"
+      filenames[${#filenames[@]}]="$suite_filename"
     done
     shopt -u nullglob
   else
-    filenames["${#filenames[@]}"]="$(expand_path "$filename")"
+    filenames[${#filenames[@]}]="$(expand_path "$filename")"
   fi
 done
 

libexec/bats-exec-test

@@ -89,7 +89,7 @@ bats_test_begin() {
 
 bats_test_function() {
   local test_name="$1"
-  BATS_TEST_NAMES["${#BATS_TEST_NAMES[@]}"]="$test_name"
+  BATS_TEST_NAMES[${#BATS_TEST_NAMES[@]}]="$test_name"
 }
 
 bats_capture_stack_trace() {
@@ -104,7 +104,7 @@ bats_capture_stack_trace() {
   local index=1
 
   while frame="$(caller "$index")"; do
-    BATS_CURRENT_STACK_TRACE["${#BATS_CURRENT_STACK_TRACE[@]}"]="$frame"
+    BATS_CURRENT_STACK_TRACE[${#BATS_CURRENT_STACK_TRACE[@]}]="$frame"
     if [[ "$frame" = *"$test_pattern"     || \
           "$frame" = *"$setup_pattern"    || \
           "$frame" = *"$teardown_pattern" ]]; then

libexec/bats-preprocess

@@ -40,7 +40,7 @@ while IFS= read -r line; do
     body="${BASH_REMATCH[2]}"
     name="$(eval echo "$quoted_name")"
     encoded_name="$(encode_name "$name")"
-    tests["${#tests[@]}"]="$encoded_name"
+    tests[${#tests[@]}]="$encoded_name"
     echo "${encoded_name}() { bats_test_begin ${quoted_name} ${index}; ${body}"
   else
     printf "%s\n" "$line"

test-with-all-bashes.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+
+set -e
+
+run_with_bash() {
+  # shellcheck disable=SC2016
+  printf 'Running tests with bash %s\n\n' "$("$1/bash" -c 'echo $BASH_VERSION')"
+
+  (
+    PATH="$1":$PATH bin/bats --tap test
+    PATH="$1":$PATH bin/bats --pretty test
+  )
+
+  printf '\n'
+}
+
+for v in 3.1 3.2 4.0 4.1 4.2 4.3 4.4 ; do
+  printf 'Building bash %s\n\n' $v
+
+  wget --quiet https://ftp.gnu.org/gnu/bash/bash-$v.tar.gz
+  tar -xf bash-$v.tar.gz
+  rm bash-$v.tar.gz
+
+  (
+    cd bash-$v
+    ./configure > /dev/null 2>&1
+    make > /dev/null 2>&1
+  )
+
+  run_with_bash bash-$v
+
+  printf 'Rebuilding bash %s with latest patch level\n\n' $v
+  (
+    cd bash-$v
+    wget -q --cut-dirs=100 -r --no-parent https://ftp.gnu.org/gnu/bash/bash-$v-patches/
+    mv ftp.gnu.org bash-$v-patches/
+    ( cd bash-$v-patches && cat bash??-??? ) | patch -s -p0 || exit 1
+    make > /dev/null 2>&1
+  )
+
+  run_with_bash bash-$v
+
+  rm -rf bash-$v
+done

test/bats.bats

@@ -131,8 +131,9 @@ fixtures bats
   PASS=1 run bats "$FIXTURE_ROOT/failing_teardown.bats"
   [ $status -eq 1 ]
   [ "${lines[1]}" = 'not ok 1 truth' ]
-  [ "${lines[2]}" = "# (from function \`teardown' in test file $RELATIVE_FIXTURE_ROOT/failing_teardown.bats, line 2)" ]
-  [ "${lines[3]}" = "#   \`eval \"( exit \${STATUS:-1} )\"' failed" ]
+  # some versions of bash 4.0.x format this error slightly differently
+  [ "${lines[2]}" = "# (from function \`teardown' in test file $RELATIVE_FIXTURE_ROOT/failing_teardown.bats, line 1)" ] || [ "${lines[2]}" = "# (from function \`teardown' in test file $RELATIVE_FIXTURE_ROOT/failing_teardown.bats, line 2)" ]
+  [ "${lines[3]}" = "#   \`teardown() {' failed" ] || [ "${lines[3]}" = "#   \`eval \"( exit \${STATUS:-1} )\"' failed" ]
 }
 
 @test "failing test with teardown failure" {
@@ -146,7 +147,8 @@ fixtures bats
 @test "teardown failure with significant status" {
   PASS=1 STATUS=2 run bats "$FIXTURE_ROOT/failing_teardown.bats"
   [ $status -eq 1 ]
-  [ "${lines[3]}" = "#   \`eval \"( exit \${STATUS:-1} )\"' failed with status 2" ]
+  # some versions of bash 4.0.x format this error slightly differently
+  [ "${lines[3]}" = "#   \`eval \"( exit \${STATUS:-1} )\"' failed with status 2" ] || [ "${lines[3]}" = "#   \`teardown() {' failed with status 2" ]
 }
 
 @test "failing test file outside of BATS_CWD" {