From 31b2faf1358fb2d3869bd62b26f453f8110d1713 Mon Sep 17 00:00:00 2001
From: Alexey Maslennikov <alexey@maslennikov.me>
Date: Fri, 16 Jun 2017 15:59:57 +0200
Subject: [PATCH] Fixing empty variable failure for --fail-not-set

---
 mo                               | 12 +++++++++++-
 tests/fail-not-set-file.sh       |  2 +-
 tests/fail-not-set-file.template |  4 +++-
 tests/fail-not-set.expected      |  4 +++-
 tests/fail-not-set.sh            |  6 +++++-
 5 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/mo b/mo
index f1d1b31..57f0fba 100755
--- a/mo
+++ b/mo
@@ -758,7 +758,7 @@ moShow() {
             echo -n "$moJoined"
         else
             # shellcheck disable=SC2031
-            if [[ -z "$MO_FAIL_ON_UNSET" ]] || moTest "$1"; then
+            if [[ -z "$MO_FAIL_ON_UNSET" ]] || moTestVarSet "$1"; then
                 echo -n "${!1}"
             else
                 echo "Env variable not set: $1" >&2
@@ -880,6 +880,16 @@ moTest() {
     return 1
 }
 
+# Internal: Determine if a variable is assigned, even if it is assigned an empty
+# value.
+#
+# $1 - Variable name to check.
+#
+# Returns true (0) if the variable is set, 1 if the variable is unset.
+moTestVarSet() {
+    [[ "${!1-a}" == "${!1-b}" ]]
+}
+
 
 # Internal: Trim the leading whitespace only.
 #
diff --git a/tests/fail-not-set-file.sh b/tests/fail-not-set-file.sh
index 0355219..fe24e85 100755
--- a/tests/fail-not-set-file.sh
+++ b/tests/fail-not-set-file.sh
@@ -2,7 +2,7 @@
 
 cd "${0%/*}"
 unset __NO_SUCH_VAR
-../mo --fail-not-set ./fail-not-set-file.template 2>&1
+POPULATED="words" EMPTY="" ../mo --fail-not-set ./fail-not-set-file.template 2>&1
 
 if [[ $? -ne 1 ]]; then
     echo "Did not return 1"
diff --git a/tests/fail-not-set-file.template b/tests/fail-not-set-file.template
index bd8b3ee..d249abe 100644
--- a/tests/fail-not-set-file.template
+++ b/tests/fail-not-set-file.template
@@ -1 +1,3 @@
-* {{__NO_SUCH_VAR}}
+Populated: {{POPULATED}};
+Empty: {{EMPTY}};
+Unset: {{__NO_SUCH_VAR}};
diff --git a/tests/fail-not-set.expected b/tests/fail-not-set.expected
index 06dea8f..6713890 100644
--- a/tests/fail-not-set.expected
+++ b/tests/fail-not-set.expected
@@ -1 +1,3 @@
-This will fail: Env variable not set: __NO_SUCH_VAR
+Populated: words;
+Empty: ;
+Unset: Env variable not set: __NO_SUCH_VAR
diff --git a/tests/fail-not-set.sh b/tests/fail-not-set.sh
index d3f9ef7..b0b6b34 100755
--- a/tests/fail-not-set.sh
+++ b/tests/fail-not-set.sh
@@ -2,7 +2,11 @@
 
 cd "${0%/*}"
 unset __NO_SUCH_VAR
-echo "This will fail: {{__NO_SUCH_VAR}}" | ../mo --fail-not-set 2>&1
+POPULATED="words" EMPTY="" ../mo --fail-not-set 2>&1 <<EOF
+Populated: {{POPULATED}};
+Empty: {{EMPTY}};
+Unset: {{__NO_SUCH_VAR}};
+EOF
 
 if [[ $? -ne 1 ]]; then
     echo "Did not return 1"