Fix pretty_format failure under set -o pipefail

Previously pretty_format used a conditional with &&. When the caller had
pipefail enabled and alt_symbol was empty, the conditional could return
a non-zero status and cause the whole pipeline to fail.

This change prevents false failures when running tests with pipefail
enabled.

Author: Aki Arvio

bash_unit

@@ -357,8 +357,8 @@ pretty_format() {
     if $term_utf8
     then
       echo -en " $pretty_symbol "
-    else
-      [[ -n "$alt_symbol" ]] && echo -en " $alt_symbol "
+    elif [[ -n "$alt_symbol" ]]; then
+      echo -en " $alt_symbol "
     fi
   ) | color "$color"
 }

tests/test_core.sh

@@ -225,6 +225,15 @@ test_should_pretty_format_even_when_LANG_is_unset() {
   assert "echo foo | pretty_format GREEN I"
 }
 
+test_should_pretty_format_even_with_pipefail_set() {
+  # pretty_success must not fail when alt_symbol is empty with pipefail set.
+  (
+    set -o pipefail
+    unset LANG
+    assert "echo foo | pretty_success"
+  )
+}
+
 if [[ "${STICK_TO_CWD:-}" != true ]]
 then
   # do not test for cwd if STICK_TO_CWD is true