From 7604ce3054eaaefbb4c414665678378975b6b414 Mon Sep 17 00:00:00 2001
From: Tyler Akins <fidian@rumkin.com>
Date: Mon, 10 Apr 2023 08:10:14 -0500
Subject: [PATCH] Pass shellcheck, more specs are handled, preserve function
 whitespace

This closes #49.
---
 mo                                | 223 +++++++++++++++---------------
 run-spec.js                       |  25 +++-
 run-tests                         |   2 +
 tests/ampersand                   |   6 +-
 tests/array                       |   2 +-
 tests/assoc-array                 |   1 +
 tests/comment                     |   4 +-
 tests/comment-newline             |   6 +-
 tests/comment-with-spaces         |   4 +-
 tests/concatenated-variables      |   8 +-
 tests/delimiters                  |   6 +-
 tests/double-hyphen               |   8 +-
 tests/double-quote                |   4 +-
 tests/fail-not-set                |  14 +-
 tests/fail-on-function            |  13 +-
 tests/false-is-empty-arg          |  12 +-
 tests/false-is-empty-env          |  10 +-
 tests/false-list                  |   8 +-
 tests/function                    |  11 +-
 tests/function-args               |   2 +-
 tests/function-args-read          |   6 +-
 tests/globals-in-loop             |   4 +-
 tests/help                        |  55 ++++++--
 tests/indented-partials           |   2 +-
 tests/internal-whitespace         |   6 +-
 tests/invalid-option              |  14 +-
 tests/inverted                    |   8 +-
 tests/list-contexts               |  10 +-
 tests/miss                        |   4 +-
 tests/multi-line-partial          |   7 +-
 tests/mush                        |  12 +-
 tests/no-content                  |   4 +-
 tests/partial                     |   2 +-
 tests/partial-bad-file            |   9 ++
 tests/partial-missing             |   7 +-
 tests/single-quote                |   4 +-
 tests/single-variable-replacement |   6 +-
 tests/source                      |   2 +-
 tests/source-bad-file             |  12 +-
 tests/source-multiple             |   2 +-
 tests/source-no-file              |   8 +-
 tests/standalone-indentation      |   2 +-
 tests/triple-brace                |   6 +-
 tests/typical                     |   8 +-
 tests/unbound-variable            |   6 +-
 tests/variable                    |   6 +-
 46 files changed, 308 insertions(+), 273 deletions(-)
 create mode 100755 tests/partial-bad-file

diff --git a/mo b/mo
index cc4f9dd..cd10964 100755
--- a/mo
+++ b/mo
@@ -15,26 +15,59 @@
 #/
 #/ Options:
 #/
+#/    --allow-function-arguments
+#/          Permit functions to be called with additional arguments. Otherwise,
+#/          the only way to get access to the arguments is to use the
+#/          MO_FUNCTION_ARGS environment variable.
+#/    -d, --debug
+#/          Enable debug logging to stderr.
 #/    -u, --fail-not-set
-#/          Fail upon expansion of an unset variable.
+#/          Fail upon expansion of an unset variable. Will silently ignore by
+#/          default. Alternately, set MO_FAIL_ON_UNSET to a non-empty value.
 #/    -x, --fail-on-function
-#/          Fail when a function returns a non-zero status code.
+#/          Fail when a function returns a non-zero status code instead of
+#/          silently ignoring it. Alternately, set MO_FAIL_ON_FUNCTION to a
+#/          non-empty value.
+#/    -f, --fail-on-file
+#/          Fail when a file (from command-line or partial) does not exist.
+#/          Alternately, set MO_FAIL_ON_FILE to a non-empty value.
 #/    -e, --false
-#/          Treat the string "false" as empty for conditionals.
+#/          Treat the string "false" as empty for conditionals. Alternately,
+#/          set MO_FALSE_IS_EMPTY to a non-empty value.
 #/    -h, --help
 #/          This message.
 #/    -s=FILE, --source=FILE
 #/          Load FILE into the environment before processing templates.
 #/          Can be used multiple times.
-#/    -d, --debug
-#/          Enable debug logging to stderr.
-#
-# Mo is under a MIT style licence with an additional non-advertising clause.
-# See LICENSE.md for the full text.
-#
-# This is open source!  Please feel free to contribute.
-#
-# https://github.com/tests-always-included/mo
+#/    --    Indicate the end of options. All arguments after this will be
+#/          treated as filenames only. Use when filenames may start with
+#/          hyphens.
+#/
+#/ Mo uses the following environment variables:
+#/
+#/ MO_ALLOW_FUNCTION_ARGUMENTS - When set to a non-empty value, this allows
+#/     functions referenced in templates to receive additional options and
+#/     arguments.
+#/ MO_DEBUG - When set to a non-empty value, additional debug information is
+#/     written to stderr.
+#/ MO_FUNCTION_ARGS - Arguments passed to the function.
+#/ MO_FAIL_ON_FILE - If a filename from the command-line is missing or a
+#/     partial does not exist, abort with an error.
+#/ MO_FAIL_ON_FUNCTION - If a function returns a non-zero status code, abort
+#/     with an error.
+#/ MO_FAIL_ON_UNSET - When set to a non-empty value, expansion of an unset env
+#/     variable will be aborted with an error.
+#/ MO_FALSE_IS_EMPTY - When set to a non-empty value, the string "false" will
+#/     be treated as an empty value for the purposes of conditionals.
+#/ MO_ORIGINAL_COMMAND - Used to find the `mo` program in order to generate a
+#/     help message.
+#/
+#/ Mo is under a MIT style licence with an additional non-advertising clause.
+#/ See LICENSE.md for the full text.
+#/
+#/ This is open source!  Please feel free to contribute.
+#/
+#/ https://github.com/tests-always-included/mo
 
 
 # Public: Template parser function.  Writes templates to stdout.
@@ -42,63 +75,7 @@
 # $0 - Name of the mo file, used for getting the help message.
 # $@ - Filenames to parse.
 #
-# Options:
-#
-#     --allow-function-arguments
-#
-# Permit functions in templates to be called with additional arguments.  This
-# puts template data directly in to the path of an eval statement. Use with
-# caution. Not listed in the help because it only makes sense when mo is
-# sourced.
-#
-#     -u, --fail-not-set
-#
-# Fail upon expansion of an unset variable.  Default behavior is to silently
-# ignore and expand into empty string.
-#
-#     -x, --fail-on-function
-#
-# Fail when a function used by a template returns an error status code.
-# Alternately, ou may set the MO_FAIL_ON_FUNCTION environment variable to a
-# non-empty value to enable this behavior.
-#
-#     -e, --false
-#
-# Treat "false" as an empty value.  You may set the MO_FALSE_IS_EMPTY
-# environment variable instead to a non-empty value to enable this behavior.
-#
-#     -h, --help
-#
-# Display a help message.
-#
-#     -s=FILE, --source=FILE
-#
-# Source a file into the environment before processing template files.
-# This can be used multiple times.
-#
-#     --
-#
-# Used to indicate the end of options.  You may optionally use this when
-# filenames may start with two hyphens.
-#
-# Mo uses the following environment variables:
-#
-# MO_ALLOW_FUNCTION_ARGUMENTS - When set to a non-empty value, this allows
-#                  functions referenced in templates to receive additional
-#                  options and arguments. This puts the content from the
-#                  template directly into an eval statement. Use with extreme
-#                  care.
-# MO_DEBUG - When set to a non-empty value, additional debug information is
-#                  written to stderr.
-# MO_FUNCTION_ARGS - Arguments passed to the function.
-# MO_FAIL_ON_FUNCTION - If a function returns a non-zero status code, abort
-#                  with an error.
-# MO_FAIL_ON_UNSET - When set to a non-empty value, expansion of an unset env
-#                  variable will be aborted with an error.
-# MO_FALSE_IS_EMPTY - When set to a non-empty value, the string "false" will be
-#                  treated as an empty value for the purposes of conditionals.
-# MO_ORIGINAL_COMMAND - Used to find the `mo` program in order to generate a
-#                  help message.
+# See the comment above for details.
 #
 # Returns nothing.
 mo() (
@@ -140,6 +117,11 @@ mo() (
                         MO_FAIL_ON_FUNCTION=true
                         ;;
 
+                    -p | --fail-on-file)
+                        # shellcheck disable=SC2030
+                        MO_FAIL_ON_FILE=true
+                        ;;
+
                     -e | --false)
                         # shellcheck disable=SC2030
                         MO_FALSE_IS_EMPTY=true
@@ -162,6 +144,7 @@ mo() (
                         ;;
 
                     -d | --debug)
+                        # shellcheck disable=SC2030
                         MO_DEBUG=true
                         ;;
 
@@ -170,6 +153,10 @@ mo() (
                         moDoubleHyphens=true
                         ;;
 
+                    -*)
+                        mo::error "Unknown option: $arg    (See --help for options)"
+                        ;;
+
                     *)
                         #: Every arg that is not a flag or a option should be a file
                         moFiles=(${moFiles[@]+"${moFiles[@]}"} "$arg")
@@ -192,6 +179,7 @@ mo() (
 #
 # Returns nothing.
 mo::debug() {
+    # shellcheck disable=SC2031
     if [[ -n "${MO_DEBUG:-}" ]]; then
         echo "DEBUG: $1" >&2
     fi
@@ -205,7 +193,7 @@ mo::debug() {
 # Returns nothing. Exits the program.
 mo::error() {
     echo "ERROR: $1" >&2
-    exit ${2:-1}
+    exit "${2:-1}"
 }
 
 
@@ -264,17 +252,26 @@ mo::content() {
 #
 # Returns nothing.
 mo::contentFile() {
-    local moContent moLen
+    local moContent moFile
 
     # The subshell removes any trailing newlines.  We forcibly add
     # a dot to the content to preserve all newlines.
     # As a future optimization, it would be worth considering removing
     # cat and replacing this with a read loop.
 
-    mo::debug "Loading content: ${2:-/dev/stdin}"
-    moContent=$(cat -- "${2:-/dev/stdin}" && echo '.') || return 1
-    moLen=$((${#moContent} - 1))
-    moContent=${moContent:0:$moLen}  # Remove last dot
+    moFile=${2:-/dev/stdin}
+
+    # shellcheck disable=SC2031
+    if [[ -e "$moFile" ]]; then
+        mo::debug "Loading content: $moFile"
+        moContent=$(cat -- "$moFile" && echo '.') || return 1
+        moContent=${moContent%.}  # Remove last dot
+    elif [[ -n "${MO_FAIL_ON_FILE-}" ]]; then
+        mo::error "No such file: $moFile"
+    else
+        mo::debug "File does not exist: $moFile"
+        moContent=""
+    fi
 
     local "$1" && mo::indirect "$1" "$moContent"
 }
@@ -384,9 +381,9 @@ mo::trim() {
     while [[ "$moContent" != "$moLast" ]]; do
         moLast=$moContent
         moContent=${moContent# }
-        moContent=${moContent#$moR}
-        moContent=${moContent#$moN}
-        moContent=${moContent#$moT}
+        moContent=${moContent#"$moR"}
+        moContent=${moContent#"$moN"}
+        moContent=${moContent#"$moT"}
     done
 
     local "$1" && mo::indirect "$1" "$moContent"
@@ -406,9 +403,9 @@ mo::chomp() {
     moN=$'\n'
     moT=$'\t'
     moTemp=${2%% *}
-    moTemp=${moTemp%%$moR*}
-    moTemp=${moTemp%%$moN*}
-    moTemp=${moTemp%%$moT*}
+    moTemp=${moTemp%%"$moR"*}
+    moTemp=${moTemp%%"$moN"*}
+    moTemp=${moTemp%%"$moT"*}
 
     local "$1" && mo::indirect "$1" "$moTemp"
 }
@@ -440,7 +437,7 @@ mo::chomp() {
 #
 # Returns nothing.
 mo::parse() {
-    local moContent moCurrent moOpenDelimiter moCloseDelimieter moResult moSplit moParseChunk moFastMode moStandaloneContent moRemainder
+    local moContent moCurrent moOpenDelimiter moCloseDelimiter moResult moSplit moParseChunk moFastMode moStandaloneContent moRemainder
     moContent=$2
     moCurrent=$3
     moCurrentBlock=$4
@@ -777,15 +774,15 @@ mo::parsePartial() {
     moCloseDelimiter=$5
     moFastMode=$6
     moStandaloneContent=$7
-    mo::chomp moFilename "${moContent%%$moCloseDelimiter*}"
-    moContent="${moContent#*$moCloseDelimiter}"
+    mo::chomp moFilename "${moContent%%"$moCloseDelimiter"*}"
+    moContent="${moContent#*"$moCloseDelimiter"}"
     moIndentation=""
 
     if mo::standaloneCheck "$moStandaloneContent" "$moContent"; then
         moN=$'\n'
         moR=$'\r'
-        moIndentation="$moN${moPrevious//$moR/$moN}"
-        moIndentation=${moIndentation##*$moN}
+        moIndentation="$moN${moPrevious//"$moR"/"$moN"}"
+        moIndentation=${moIndentation##*"$moN"}
         mo::debug "Adding indentation to partial: '$moIndentation'"
         mo::standaloneProcessBefore moPrevious "$moPrevious"
         mo::standaloneProcessAfter moContent "$moContent"
@@ -796,7 +793,6 @@ mo::parsePartial() {
 
     if [[ -n "$moFastMode" ]]; then
         moResult=""
-        moLen=0
     else
         mo::debug "Parsing partial: $moFilename"
 
@@ -901,7 +897,7 @@ mo::parseComment() {
     moContent=$3
     moCloseDelimiter=$4
     moStandaloneContent=$5
-    moContent=${moContent#*$moCloseDelimiter}
+    moContent=${moContent#*"$moCloseDelimiter"}
     mo::debug "Parsing comment"
 
     if mo::standaloneCheck "$moStandaloneContent" "$moContent"; then
@@ -942,8 +938,8 @@ mo::parseDelimiter() {
     mo::chomp moOpen "$moContent"
     moContent=${moContent:${#moOpen}}
     mo::trim moContent "$moContent"
-    moClose="${moContent%%=$moCloseDelimiter*}"
-    moContent=${moContent#*=$moCloseDelimiter}
+    moClose="${moContent%%="$moCloseDelimiter"*}"
+    moContent=${moContent#*="$moCloseDelimiter"}
     mo::debug "Parsing delimiters: $moOpen $moClose"
 
     if mo::standaloneCheck "$moStandaloneContent" "$moContent"; then
@@ -983,7 +979,7 @@ mo::parseValue() {
     moOpenDelimiter=$5
     moCloseDelimiter=$6
     moFastMode=$7
-    mo::trim moContent "${moContentOriginal#$moOpenDelimiter}"
+    mo::trim moContent "${moContentOriginal#"$moOpenDelimiter"}"
 
     mo::parseValueInner moArgs "$moContent" "$moCurrent" "$moCloseDelimiter"
     moContent=${moArgs[0]}
@@ -1252,7 +1248,7 @@ mo::getArgumentDefault() {
     local moTemp moContent
 
     moTemp=$2
-    mo::chomp moTemp "${moTemp%%$3*}"
+    mo::chomp moTemp "${moTemp%%"$3"*}"
     moTemp=${moTemp%%)*}
     moTemp=${moTemp%%\}*}
     moContent=${2:${#moTemp}}
@@ -1384,6 +1380,7 @@ mo::isTruthy() {
 
     moTruthy=true
 
+    # shellcheck disable=SC2031
     if [[ -z "${1-}" ]]; then
         moTruthy=false
     elif [[ -n "${MO_FALSE_IS_EMPTY-}" ]] && [[ "${1-}" == "false" ]]; then
@@ -1533,7 +1530,7 @@ mo::evaluateKey() {
 #
 # Returns nothing.
 mo::evaluateVariable() {
-    local moResult moCurrent moArg moNameParts moJoined moKey moValue
+    local moResult moCurrent moArg moNameParts
 
     moArg=$2
     moCurrent=$3
@@ -1543,7 +1540,7 @@ mo::evaluateVariable() {
 
     if [[ -z "${moNameParts[1]}" ]]; then
         if mo::isArray "$moArg"; then
-            eval mo::join moResult "," "\${$moArg[@]}"
+            eval mo::join moResult "," "\${${moArg}[@]}"
         else
             # shellcheck disable=SC2031
             if mo::isVarSet "$moArg"; then
@@ -1560,7 +1557,7 @@ mo::evaluateVariable() {
         fi
     fi
 
-    local $1 && mo::indirect "$1" "$moResult"
+    local "$1" && mo::indirect "$1" "$moResult"
 }
 
 
@@ -1648,7 +1645,7 @@ moJoin() {
 #
 # Returns nothing.
 mo::evaluateFunction() {
-    local moArgs moContent moFunctionArgs moFunctionResult moTarget moFunction moTemp moFunctionCall
+    local moArgs moContent moFunctionResult moTarget moFunction moTemp moFunctionCall
 
     moTarget=$1
     moContent=$2
@@ -1675,16 +1672,18 @@ mo::evaluateFunction() {
     fi
 
     mo::debug "Calling function: $moFunctionCall"
-    moContent=$(export MO_FUNCTION_ARGS=("${moArgs[@]}"); echo -n "$moContent" | eval "$moFunctionCall") || {
+
+    # Call the function in a subshell for safety. Employ the trick to preserve
+    # whitespace at the end of the output.
+    moContent=$(export MO_FUNCTION_ARGS=("${moArgs[@]}"); echo -n "$moContent" | eval "$moFunctionCall ; moFunctionResult=\$? ; echo -n '.' ; exit \"\$moFunctionResult\"") || {
         moFunctionResult=$?
         # shellcheck disable=SC2031
         if [[ -n "${MO_FAIL_ON_FUNCTION-}" && "$moFunctionResult" != 0 ]]; then
-            mo::error "Function '$moFunction' with args (${moArgs[@]+"${moArgs[@]}"}) failed with status code $moFunctionResult" "$moFunctionResult"
+            mo::error "Function failed with status code $moFunctionResult: $moFunctionCall" "$moFunctionResult"
         fi
     }
 
-    # shellcheck disable=SC2031
-    local "$moTarget" && mo::indirect "$moTarget" "$moContent"
+    local "$moTarget" && mo::indirect "$moTarget" "${moContent%.}"
 }
 
 
@@ -1704,7 +1703,7 @@ mo::standaloneCheck() {
     moT=$'\t'
 
     # Check the content before
-    moContent=${1//$moR/$moN}
+    moContent=${1//"$moR"/"$moN"}
 
     if [[ "$moContent" != *"$moN"* ]]; then
         mo::debug "Not a standalone tag - no newline before"
@@ -1712,8 +1711,8 @@ mo::standaloneCheck() {
         return 1
     fi
 
-    moContent=${moContent##*$moN}
-    moContent=${moContent//$moT/}
+    moContent=${moContent##*"$moN"}
+    moContent=${moContent//"$moT"/}
     moContent=${moContent// /}
 
     if [[ -n "$moContent" ]]; then
@@ -1723,9 +1722,9 @@ mo::standaloneCheck() {
     fi
 
     # Check the content after
-    moContent=${2//$moR/$moN}
-    moContent=${moContent%%$moN*}
-    moContent=${moContent//$moT/}
+    moContent=${2//"$moR"/"$moN"}
+    moContent=${moContent%%"$moN"*}
+    moContent=${moContent//"$moT"/}
     moContent=${moContent// /}
 
     if [[ -n "$moContent" ]]; then
@@ -1756,7 +1755,7 @@ mo::standaloneProcessBefore() {
     while [[ "$moLast" != "$moContent" ]]; do
         moLast=$moContent
         moContent=${moContent% }
-        moContent=${moContent%$moT}
+        moContent=${moContent%"$moT"}
     done
 
     local "$1" && mo::indirect "$1" "$moContent"
@@ -1783,11 +1782,11 @@ mo::standaloneProcessAfter() {
     while [[ "$moLast" != "$moContent" ]]; do
         moLast=$moContent
         moContent=${moContent# }
-        moContent=${moContent#$moT}
+        moContent=${moContent#"$moT"}
     done
 
-    moContent=${moContent#$moR}
-    moContent=${moContent#$moN}
+    moContent=${moContent#"$moR"}
+    moContent=${moContent#"$moN"}
 
     local "$1" && mo::indirect "$1" "$moContent"
 }
@@ -1816,8 +1815,8 @@ mo::indentLines() {
         mo::debug "Applying indentation: '${moIndentation}'"
 
         while [[ -n "$moContent" ]]; do
-            moChunk=${moContent%%$moN*}
-            moChunk=${moChunk%%$moR*}
+            moChunk=${moContent%%"$moN"*}
+            moChunk=${moChunk%%"$moR"*}
             moContent=${moContent:${#moChunk}}
 
             if [[ -n "$moChunk" ]]; then
diff --git a/run-spec.js b/run-spec.js
index ad41931..59fd738 100644
--- a/run-spec.js
+++ b/run-spec.js
@@ -11,6 +11,12 @@ const fsPromises = require("fs").promises;
 //
 // To override any test property, just define that property.
 const testOverrides = {
+    "Comments -> Variable Name Collision": {
+        // Can't use variables with exclamation points easily
+        data: {
+            comment: 4
+        }
+    },
     "Interpolation -> HTML Escaping": {
         skip: "HTML escaping is not supported"
     },
@@ -20,6 +26,9 @@ const testOverrides = {
     "Lambdas -> Escaping": {
         skip: "HTML escaping is not supported"
     },
+    "Partials -> Recursion": {
+        skip: "Complex objects are not supported and context is reset to the global level, so the recursion will loop forever"
+    },
     "Sections -> Deeply Nested Contexts": {
         skip: "Nested objects are not supported"
     },
@@ -268,6 +277,7 @@ function applyTestOverrides(test) {
         test[key] = value;
     }
 
+    test.overridesApplied = true;
     test.valuesBeforeOverride = originals;
 }
 
@@ -310,6 +320,7 @@ function processSpecFile(filename) {
             testSet.pass = 0;
             testSet.fail = 0;
             testSet.skip = 0;
+            testSet.passOverride = 0;
 
             for (const test of testSet.tests) {
                 if (test.isFailure) {
@@ -318,10 +329,14 @@ function processSpecFile(filename) {
                     testSet.skip += 1;
                 } else {
                     testSet.pass += 1;
+
+                    if (test.overridesApplied) {
+                        testSet.passOverride += 1;
+                    }
                 }
             }
             console.log(
-                `### ${testSet.name} Results = ${testSet.pass} passed, ${testSet.fail} failed, ${testSet.skip} skipped`
+                `### ${testSet.name} Results = ${testSet.pass} passed (with ${testSet.passOverride} overridden), ${testSet.fail} failed, ${testSet.skip} skipped`
             );
 
             return testSet;
@@ -344,16 +359,18 @@ processArraySequentially(process.argv.slice(2), processSpecFile).then(
         let pass = 0,
             fail = 0,
             skip = 0,
-            total = 0;
+            total = 0,
+            passOverride = 0;
 
         for (const testSet of result) {
             pass += testSet.pass;
             fail += testSet.fail;
             skip += testSet.skip;
             total += testSet.tests.length;
+            passOverride += testSet.passOverride;
 
             console.log(
-                `* ${testSet.name}: ${testSet.tests.length} total, ${testSet.pass} pass, ${testSet.fail} fail, ${testSet.skip} skip`
+                `* ${testSet.name}: ${testSet.tests.length} total, ${testSet.pass} pass (with ${passOverride} overridden), ${testSet.fail} fail, ${testSet.skip} skip`
             );
 
             for (const test of testSet.tests) {
@@ -365,7 +382,7 @@ processArraySequentially(process.argv.slice(2), processSpecFile).then(
 
         console.log("");
         console.log(
-            `Final result: ${total} total, ${pass} pass, ${fail} fail, ${skip} skip`
+            `Final result: ${total} total, ${pass} pass (with ${passOverride} overridden), ${fail} fail, ${skip} skip`
         );
 
         if (fail) {
diff --git a/run-tests b/run-tests
index 84b0212..04ec115 100755
--- a/run-tests
+++ b/run-tests
@@ -52,6 +52,8 @@ runTest() (
 
         if [[ -n "${MO_DEBUG_TEST-}" ]]; then
             declare -p testExpected
+            # Align the two declare outputs
+            echo -n "  "
             declare -p testActual
         fi
 
diff --git a/tests/ampersand b/tests/ampersand
index 735babf..ff8914f 100755
--- a/tests/ampersand
+++ b/tests/ampersand
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-thing="Works"
-template="{{&thing}}"
-expected="Works"
+export thing="Works"
+export template="{{&thing}}"
+export expected="Works"
 
 runTest
diff --git a/tests/array b/tests/array
index 9e9340d..6ca5a2b 100755
--- a/tests/array
+++ b/tests/array
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-repo=( "resque" "hub" "rip" )
+export repo=( "resque" "hub" "rip" )
 template() {
     cat <<EOF
 {{#repo}}
diff --git a/tests/assoc-array b/tests/assoc-array
index dffa3b1..cf73494 100755
--- a/tests/assoc-array
+++ b/tests/assoc-array
@@ -6,6 +6,7 @@ declare -A repo
 repo[resque]="Resque"
 repo[hub]="Hub"
 repo[rip]="Rip"
+export repo
 template() {
     cat <<EOF
 {{#repo}}
diff --git a/tests/comment b/tests/comment
index 73ccfb9..7a8708d 100755
--- a/tests/comment
+++ b/tests/comment
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-template="Wor{{!comment}}ks"
-expected="Works"
+export template="Wor{{!comment}}ks"
+export expected="Works"
 
 runTest
diff --git a/tests/comment-newline b/tests/comment-newline
index a308529..0c1fea8 100755
--- a/tests/comment-newline
+++ b/tests/comment-newline
@@ -10,10 +10,6 @@ run through multiple
 lines}}.</h1>
 EOF
 }
-expected() {
-    cat <<EOF
-<h1>Today.</h1>
-EOF
-}
+export expected=$'<h1>Today.</h1>\n'
 
 runTest
diff --git a/tests/comment-with-spaces b/tests/comment-with-spaces
index 3e226d3..c8f8d5b 100755
--- a/tests/comment-with-spaces
+++ b/tests/comment-with-spaces
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-template="Wor{{! comment }}ks"
-expected="Works"
+export template="Wor{{! comment }}ks"
+export expected="Works"
 
 runTest
diff --git a/tests/concatenated-variables b/tests/concatenated-variables
index 0b5772e..0bd06aa 100755
--- a/tests/concatenated-variables
+++ b/tests/concatenated-variables
@@ -2,9 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-thing="Wor"
-thing2="ks"
-template="{{thing thing2}}"
-expected="Works"
+export thing="Wor"
+export thing2="ks"
+export template="{{thing thing2}}"
+export expected="Works"
 
 runTest
diff --git a/tests/delimiters b/tests/delimiters
index 5a80429..a041811 100755
--- a/tests/delimiters
+++ b/tests/delimiters
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-thing="Works"
-template="{{=| |=}}|thing|"
-expected="Works"
+export thing="Works"
+export template="{{=| |=}}|thing|"
+export expected="Works"
 
 runTest
diff --git a/tests/double-hyphen b/tests/double-hyphen
index d841b79..3fc8d48 100755
--- a/tests/double-hyphen
+++ b/tests/double-hyphen
@@ -2,9 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-arguments=(-- --help)
-returnCode=1
-template=""
-expected="cat: --help: No such file or directory"$'\n'
+export arguments=(--fail-on-file -- --help)
+export returnCode=1
+export template=""
+export expected=$'ERROR: No such file: --help\n'
 
 runTest
diff --git a/tests/double-quote b/tests/double-quote
index d5b9ec0..526ac6a 100755
--- a/tests/double-quote
+++ b/tests/double-quote
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-template='{{"Works"}}'
-expected="Works"
+export template='{{"Works"}}'
+export expected="Works"
 
 runTest
diff --git a/tests/fail-not-set b/tests/fail-not-set
index bfab1da..3104367 100755
--- a/tests/fail-not-set
+++ b/tests/fail-not-set
@@ -3,10 +3,10 @@ cd "${0%/*}" || exit 1
 . ../run-tests
 
 unset __NO_SUCH_VAR
-POPULATED="words"
-EMPTY=""
-arguments=(--fail-not-set)
-returnCode=1
+export POPULATED="words"
+export EMPTY=""
+export arguments=(--fail-not-set)
+export returnCode=1
 
 template() {
     cat <<EOF
@@ -15,10 +15,6 @@ Empty: {{EMPTY}};
 Unset: {{__NO_SUCH_VAR}};
 EOF
 }
-expected() {
-    cat <<EOF
-ERROR: Environment variable not set: __NO_SUCH_VAR
-EOF
-}
+export expected=$'ERROR: Environment variable not set: __NO_SUCH_VAR\n'
 
 runTest
diff --git a/tests/fail-on-function b/tests/fail-on-function
index 86d446d..735d77d 100755
--- a/tests/fail-on-function
+++ b/tests/fail-on-function
@@ -5,14 +5,9 @@ cd "${0%/*}" || exit 1
 failFunction() {
     false
 }
-arguments=(--fail-on-function)
-returnCode=1
-
-template="Fail on function? {{failFunction}}"
-expected() {
-    cat <<EOF
-ERROR: Function 'failFunction' with args () failed with status code 1
-EOF
-}
+export arguments=(--fail-on-function)
+export returnCode=1
+export template="Fail on function? {{failFunction}}"
+export expected=$'ERROR: Function failed with status code 1: "failFunction"\n'
 
 runTest
diff --git a/tests/false-is-empty-arg b/tests/false-is-empty-arg
index 901ea1e..9a8d4e7 100755
--- a/tests/false-is-empty-arg
+++ b/tests/false-is-empty-arg
@@ -2,9 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-USER=j.doe
-ADMIN=false
-arguments=(--false)
+export USER=j.doe
+export ADMIN=false
+export arguments=(--false)
 template() {
     cat <<EOF
 The user {{USER}} exists.
@@ -13,10 +13,6 @@ WRONG - should not be an admin.
 {{/ADMIN}}
 EOF
 }
-expected() {
-    cat <<EOF
-The user j.doe exists.
-EOF
-}
+export expected=$'The user j.doe exists.\n'
 
 runTest
diff --git a/tests/false-is-empty-env b/tests/false-is-empty-env
index 26861dd..169f323 100755
--- a/tests/false-is-empty-env
+++ b/tests/false-is-empty-env
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-USER=j.doe
-ADMIN=false
+export USER=j.doe
+export ADMIN=false
 MO_FALSE_IS_EMPTY=yeppers
 template() {
     cat <<EOF
@@ -13,10 +13,6 @@ WRONG - should not be an admin.
 {{/ADMIN}}
 EOF
 }
-expected() {
-    cat <<EOF
-The user j.doe exists.
-EOF
-}
+export expected=$'The user j.doe exists.\n'
 
 runTest
diff --git a/tests/false-list b/tests/false-list
index bcd185a..33200f0 100755
--- a/tests/false-list
+++ b/tests/false-list
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-person=""
+export person=""
 template() {
     cat <<EOF
 Shown.
@@ -11,10 +11,6 @@ Shown.
 {{/person}}
 EOF
 }
-expected() {
-    cat <<EOF
-Shown.
-EOF
-}
+export expected=$'Shown.\n'
 
 runTest
diff --git a/tests/function b/tests/function
index e42597e..83253bd 100755
--- a/tests/function
+++ b/tests/function
@@ -2,9 +2,10 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-name=Willy
+export name=Willy
 wrapped() {
-    # This eats the newline in the content
+    # Wrapping 'cat' in a subshell eats the trailing whitespace
+    # The echo adds a newline, which is preserved.
     echo "<b>$(cat)</b>"
 }
 template() {
@@ -15,10 +16,6 @@ template() {
 ... this is the last line.
 EOF
 }
-expected() {
-    cat <<EOF
-<b>  Willy is awesome.</b>... this is the last line.
-EOF
-}
+export expected=$'<b>  Willy is awesome.</b>\n... this is the last line.\n'
 
 runTest
diff --git a/tests/function-args b/tests/function-args
index 8bbab4a..94cb55d 100755
--- a/tests/function-args
+++ b/tests/function-args
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-name=Willy
+export name=Willy
 MO_ALLOW_FUNCTION_ARGUMENTS=true
 
 pipeTo() {
diff --git a/tests/function-args-read b/tests/function-args-read
index e398fcf..e75080f 100755
--- a/tests/function-args-read
+++ b/tests/function-args-read
@@ -3,8 +3,10 @@ cd "${0%/*}" || exit 1
 . ../run-tests
 
 testArgs() {
-    local args=$(declare -p MO_FUNCTION_ARGS)
-    echo "${args#*=}"
+    local args
+    # shellcheck disable=SC2031
+    args=$(declare -p MO_FUNCTION_ARGS)
+    echo -n "${args#*=}"
 }
 template() {
     cat <<EOF
diff --git a/tests/globals-in-loop b/tests/globals-in-loop
index e4f223b..538d5f1 100755
--- a/tests/globals-in-loop
+++ b/tests/globals-in-loop
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-STR=abc
-DATA=(111 222)
+export STR=abc
+export DATA=(111 222)
 template() {
     cat <<EOF
 Issue #7
diff --git a/tests/help b/tests/help
index 32a6f4b..054b4d2 100755
--- a/tests/help
+++ b/tests/help
@@ -2,10 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-template=""
-arguments=(--help)
+export arguments=(--help)
 expected() {
-    cat <<EOF
+    cat <<'EOF'
 Mo is a mustache template rendering software written in bash.  It inserts
 environment variables into templates.
 
@@ -21,19 +20,59 @@ Simple usage:
 
 Options:
 
+   --allow-function-arguments
+         Permit functions to be called with additional arguments. Otherwise,
+         the only way to get access to the arguments is to use the
+         MO_FUNCTION_ARGS environment variable.
+   -d, --debug
+         Enable debug logging to stderr.
    -u, --fail-not-set
-         Fail upon expansion of an unset variable.
+         Fail upon expansion of an unset variable. Will silently ignore by
+         default. Alternately, set MO_FAIL_ON_UNSET to a non-empty value.
    -x, --fail-on-function
-         Fail when a function returns a non-zero status code.
+         Fail when a function returns a non-zero status code instead of
+         silently ignoring it. Alternately, set MO_FAIL_ON_FUNCTION to a
+         non-empty value.
+   -f, --fail-on-file
+         Fail when a file (from command-line or partial) does not exist.
+         Alternately, set MO_FAIL_ON_FILE to a non-empty value.
    -e, --false
-         Treat the string "false" as empty for conditionals.
+         Treat the string "false" as empty for conditionals. Alternately,
+         set MO_FALSE_IS_EMPTY to a non-empty value.
    -h, --help
          This message.
    -s=FILE, --source=FILE
          Load FILE into the environment before processing templates.
          Can be used multiple times.
-   -d, --debug
-         Enable debug logging to stderr.
+   --    Indicate the end of options. All arguments after this will be
+         treated as filenames only. Use when filenames may start with
+         hyphens.
+
+Mo uses the following environment variables:
+
+MO_ALLOW_FUNCTION_ARGUMENTS - When set to a non-empty value, this allows
+    functions referenced in templates to receive additional options and
+    arguments.
+MO_DEBUG - When set to a non-empty value, additional debug information is
+    written to stderr.
+MO_FUNCTION_ARGS - Arguments passed to the function.
+MO_FAIL_ON_FILE - If a filename from the command-line is missing or a
+    partial does not exist, abort with an error.
+MO_FAIL_ON_FUNCTION - If a function returns a non-zero status code, abort
+    with an error.
+MO_FAIL_ON_UNSET - When set to a non-empty value, expansion of an unset env
+    variable will be aborted with an error.
+MO_FALSE_IS_EMPTY - When set to a non-empty value, the string "false" will
+    be treated as an empty value for the purposes of conditionals.
+MO_ORIGINAL_COMMAND - Used to find the `mo` program in order to generate a
+    help message.
+
+Mo is under a MIT style licence with an additional non-advertising clause.
+See LICENSE.md for the full text.
+
+This is open source!  Please feel free to contribute.
+
+https://github.com/tests-always-included/mo
 
 MO_VERSION=3.0.0
 EOF
diff --git a/tests/indented-partials b/tests/indented-partials
index d9eafb9..2467c61 100755
--- a/tests/indented-partials
+++ b/tests/indented-partials
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-thisIsTrue=true
+export thisIsTrue=true
 template() {
     cat <<EOF
 With spacing
diff --git a/tests/internal-whitespace b/tests/internal-whitespace
index 59ec351..8228215 100755
--- a/tests/internal-whitespace
+++ b/tests/internal-whitespace
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-boolean=true
-template=$' | {{#boolean}} {{! Important Whitespace }}\n {{/boolean}} | \n'
-expected=$' |  \n  | \n'
+export boolean=true
+export template=$' | {{#boolean}} {{! Important Whitespace }}\n {{/boolean}} | \n'
+export expected=$' |  \n  | \n'
 
 runTest
diff --git a/tests/invalid-option b/tests/invalid-option
index 5840c88..bba194e 100755
--- a/tests/invalid-option
+++ b/tests/invalid-option
@@ -2,14 +2,10 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-person=""
-template=""
-returnCode=1
-arguments=(--something)
-expected() {
-    cat <<EOF
-cat: --something: No such file or directory
-EOF
-}
+export person=""
+export template=""
+export returnCode=1
+export arguments=(--something)
+export expected=$'ERROR: Unknown option: --something    (See --help for options)\n'
 
 runTest
diff --git a/tests/inverted b/tests/inverted
index b9ad9ed..f706a04 100755
--- a/tests/inverted
+++ b/tests/inverted
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-repo=()
+export repo=()
 template() {
     cat <<EOF
 {{#repo}}
@@ -13,10 +13,6 @@ template() {
 {{/repo}}
 EOF
 }
-expected() {
-    cat <<EOF
-  No repos :(
-EOF
-}
+export expected=$'  No repos :(\n'
 
 runTest
diff --git a/tests/list-contexts b/tests/list-contexts
index 97c9a70..9025d9b 100755
--- a/tests/list-contexts
+++ b/tests/list-contexts
@@ -2,13 +2,15 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-a=foo
-b=wrong
+export a=foo
+export b=wrong
 declare -A sec
 sec=([b]="bar")
+export sec
 declare -A c
 c=([d]="baz")
-template="{{#sec}}{{a}} {{b}} {{c.d}}{{/sec}}"
-expected="foo bar baz"
+export c
+export template="{{#sec}}{{a}} {{b}} {{c.d}}{{/sec}}"
+export expected="foo bar baz"
 
 runTest
diff --git a/tests/miss b/tests/miss
index 3010c31..900f070 100755
--- a/tests/miss
+++ b/tests/miss
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-name="Chris"
-company="<b>GitHub</b>"
+export name="Chris"
+export company="<b>GitHub</b>"
 template() {
     cat <<EOF
 * .{{name}}.
diff --git a/tests/multi-line-partial b/tests/multi-line-partial
index 7137f5b..0922f69 100755
--- a/tests/multi-line-partial
+++ b/tests/multi-line-partial
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-multilineData=$'line 1\nline 2'
+export multilineData=$'line 1\nline 2'
 template() {
     cat <<EOF
 Partial:
@@ -26,7 +26,10 @@ Indented:
     line 1
 line 2
 EOF
-    # This one looks odd, but if you check the spec spec/specs/partials.yaml, name "Standalone Indentation" (mirrors "standalone-indentation" in tests/), then the spec clearly shows that the indentation is applied before rendering.
+    # This one looks odd, but if you check the spec spec/specs/partials.yaml,
+    # name "Standalone Indentation" (mirrors "standalone-indentation" in
+    # tests/), then the spec clearly shows that the indentation is applied
+    # before rendering.
 }
 
 runTest
diff --git a/tests/mush b/tests/mush
index 349da33..c0c2354 100755
--- a/tests/mush
+++ b/tests/mush
@@ -2,12 +2,12 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-USER=jwerle
-GENDER=male
-THING=apple
-COLOR=red
-PERSON=tobi
-ADJECTIVE=cool
+export USER=jwerle
+export GENDER=male
+export THING=apple
+export COLOR=red
+export PERSON=tobi
+export ADJECTIVE=cool
 template() {
     cat <<EOF
 {{! this is a comment }}
diff --git a/tests/no-content b/tests/no-content
index fe23be3..d6d6707 100755
--- a/tests/no-content
+++ b/tests/no-content
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-template="Works"
-expected="Works"
+export template="Works"
+export expected="Works"
 
 runTest
diff --git a/tests/partial b/tests/partial
index 8dd1079..07d1c9b 100755
--- a/tests/partial
+++ b/tests/partial
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-names=( "Tyler" )
+export names=( "Tyler" )
 template() {
     cat <<EOF
 <h2>Names</h2>
diff --git a/tests/partial-bad-file b/tests/partial-bad-file
new file mode 100755
index 0000000..94906fa
--- /dev/null
+++ b/tests/partial-bad-file
@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+cd "${0%/*}" || exit 1
+. ../run-tests
+
+# This file intentionally does not exist
+export template="{{>fixtures/partial-bad-file.partial}}"
+export expected=""
+
+runTest
diff --git a/tests/partial-missing b/tests/partial-missing
index a20871b..6ca5b7b 100755
--- a/tests/partial-missing
+++ b/tests/partial-missing
@@ -2,8 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-returnCode=1
-person=""
+export returnCode=1
+export arguments=(--fail-on-file)
+export person=""
 template() {
     cat <<EOF
 Won't be there: {{> fixtures/partial-missing.partial}}
@@ -11,7 +12,7 @@ EOF
 }
 expected() {
     cat <<EOF
-cat: partial-missing.partial: No such file or directory
+ERROR: No such file: partial-missing.partial
 EOF
 }
 
diff --git a/tests/single-quote b/tests/single-quote
index 1d4a013..319fe22 100755
--- a/tests/single-quote
+++ b/tests/single-quote
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-template="{{'Works'}}"
-expected="Works"
+export template="{{'Works'}}"
+export expected="Works"
 
 runTest
diff --git a/tests/single-variable-replacement b/tests/single-variable-replacement
index edeca0e..26c5da6 100755
--- a/tests/single-variable-replacement
+++ b/tests/single-variable-replacement
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-thing="Works"
-template="{{thing}}"
-expected="Works"
+export thing="Works"
+export template="{{thing}}"
+export expected="Works"
 
 runTest
diff --git a/tests/source b/tests/source
index 2db9d8e..6f67e6e 100755
--- a/tests/source
+++ b/tests/source
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-arguments=(--source=fixtures/source.vars)
+export arguments=(--source=fixtures/source.vars)
 template() {
     cat <<EOF
 {{VAR}}
diff --git a/tests/source-bad-file b/tests/source-bad-file
index 27a8e50..6fb5840 100755
--- a/tests/source-bad-file
+++ b/tests/source-bad-file
@@ -2,13 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-arguments=(--source=invalid)
-returnCode=1
-template="Do not display this"
-expected() {
-    cat <<EOF
-No such file: invalid
-EOF
-}
+export arguments=(--source=invalid)
+export returnCode=1
+export template="Do not display this"
+export expected=$'No such file: invalid\n'
 
 runTest
diff --git a/tests/source-multiple b/tests/source-multiple
index c6670f5..4261158 100755
--- a/tests/source-multiple
+++ b/tests/source-multiple
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-arguments=(--source=fixtures/source-multiple-1.vars --source=fixtures/source-multiple-2.vars)
+export arguments=(--source=fixtures/source-multiple-1.vars --source=fixtures/source-multiple-2.vars)
 template() {
     cat <<EOF
 A: {{A}}
diff --git a/tests/source-no-file b/tests/source-no-file
index 55a691a..7934e67 100755
--- a/tests/source-no-file
+++ b/tests/source-no-file
@@ -2,9 +2,9 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-arguments=(--source=)
-returnCode=1
-template="Do not display this"
-expected=$'No such file: \n'
+export arguments=(--source=)
+export returnCode=1
+export template="Do not display this"
+export expected=$'No such file: \n'
 
 runTest
diff --git a/tests/standalone-indentation b/tests/standalone-indentation
index d3b51c0..466d182 100755
--- a/tests/standalone-indentation
+++ b/tests/standalone-indentation
@@ -2,7 +2,7 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-content=$'<\n->'
+export content=$'<\n->'
 template() {
     cat <<EOF
 \
diff --git a/tests/triple-brace b/tests/triple-brace
index a85b17c..1eb3616 100755
--- a/tests/triple-brace
+++ b/tests/triple-brace
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-thing="Works"
-template="{{{thing}}}"
-expected="Works"
+export thing="Works"
+export template="{{{thing}}}"
+export expected="Works"
 
 runTest
diff --git a/tests/typical b/tests/typical
index e7ad27d..2274852 100755
--- a/tests/typical
+++ b/tests/typical
@@ -2,10 +2,10 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-NAME="Chris"
-VALUE=10000
-TAXED_VALUE=6000
-IN_CA=true
+export NAME="Chris"
+export VALUE=10000
+export TAXED_VALUE=6000
+export IN_CA=true
 template() {
     cat <<EOF
 Hello {{NAME}}
diff --git a/tests/unbound-variable b/tests/unbound-variable
index befe7a9..0e0bc57 100755
--- a/tests/unbound-variable
+++ b/tests/unbound-variable
@@ -3,8 +3,8 @@ cd "${0%/*}" || exit 1
 . ../run-tests
 
 declare -A a
-a=()
-template="o{{#a.b}}WRONG{{/a.b}}k"
-expected="ok"
+export a=()
+export template="o{{#a.b}}WRONG{{/a.b}}k"
+export expected="ok"
 
 runTest
diff --git a/tests/variable b/tests/variable
index 9897606..d5c6c97 100755
--- a/tests/variable
+++ b/tests/variable
@@ -2,8 +2,8 @@
 cd "${0%/*}" || exit 1
 . ../run-tests
 
-foo=bar
-template="{{#foo}}{{.}} is {{foo}}{{/foo}}"
-expected="bar is bar"
+export foo=bar
+export template="{{#foo}}{{.}} is {{foo}}{{/foo}}"
+export expected="bar is bar"
 
 runTest