Fallback to using ls if /bin/ls does not exist (#22)

test/003_ls_program.bats

@@ -0,0 +1,66 @@
+load common
+load_fixtures
+
+@test "Default /bin/ls" {
+  echo "
+    By default, the value of LS_PROGRAM should be /bin/ls
+  "
+
+  # shellcheck source=/dev/null
+  YADM_TEST=1 source "$T_YADM"
+  status=0
+  output=$( require_ls; echo "$LS_PROGRAM" ) || {
+    status=$?
+    true
+  }
+
+  echo "output=$output"
+
+  [ "$status" == 0 ]
+  [ "$output" = "/bin/ls" ]
+}
+
+@test "Fallback on 'ls'" {
+  echo "
+    When LS_PROGRAM doesn't exist, use 'ls'
+  "
+
+  # shellcheck source=/dev/null
+  YADM_TEST=1 source "$T_YADM"
+  status=0
+  LS_PROGRAM="/ls/missing"
+  output=$( require_ls; echo "$LS_PROGRAM" ) || {
+    status=$?
+    true
+  }
+
+  echo "output=$output"
+
+  [ "$status" == 0 ]
+  [ "$output" = "ls" ]
+}
+
+@test "Fail if ls isn't in PATH" {
+  echo "
+    When LS_PROGRAM doesn't exist, use 'ls'
+  "
+
+  # shellcheck source=/dev/null
+  YADM_TEST=1 source "$T_YADM"
+  status=0
+  LS_PROGRAM="/ls/missing"
+  savepath="$PATH"
+  # shellcheck disable=SC2123
+  PATH=
+  output=$( require_ls 2>&1; echo "$LS_PROGRAM" ) || {
+    status=$?
+    true
+  }
+  PATH="$savepath"
+
+  echo "output=$output"
+
+  [ "$status" != 0 ]
+  [[ "$output" =~ functionality\ requires\ .ls.\ to\ be\ installed ]]
+}
+