Merge pull request #631 from martin-schulze-vireso/feature/also_show_…

…stderr_with_--print-output-on-failure

Also print $stderr (from `run --separate-stderr`) for `--print-output-on-failure`

docs/CHANGELOG.md

@@ -21,6 +21,8 @@ The format is based on [Keep a Changelog][kac] and this project adheres to
   avoiding `bash: bats: No such file or directory` on `docker<20.10` (or
   `runc<v1.0.0-rc93`) (#622)
 * `BATS_TEST_TIMEOUT` variable to force a timeout on test (including `setup()`) (#491)
+* also print (nonempty) `$stderr` (from `run --separate-stderr`) with
+  `--print-output-on-failure` (#631)
 
 #### Documentation
 

lib/bats-core/test_functions.bash

@@ -261,7 +261,7 @@ run() { # [!|-N] [--keep-empty-lines] [--separate-stderr] [--] <command to run..
 
   if [[ "$output_case" == separate ]]; then
       # shellcheck disable=SC2034
-      read -d '' -r stderr < "$bats_run_separate_stderr_file"
+      read -d '' -r stderr < "$bats_run_separate_stderr_file" || true
       bats_separate_lines stderr_lines stderr
   fi
 

libexec/bats-core/bats-exec-test

@@ -162,9 +162,14 @@ bats_exit_trap() {
       bats_print_stack_trace "${stack_trace[@]}" >&3
       bats_print_failed_command "${stack_trace[@]}" >&3
 
-      if [[ $BATS_PRINT_OUTPUT_ON_FAILURE && -n "${output:-}" ]]; then
-        printf "Last output:\n%s\n" "$output" >> "$BATS_OUT"
-      fi 
+      if [[ $BATS_PRINT_OUTPUT_ON_FAILURE ]]; then
+        if [[ -n "${output:-}" ]]; then
+          printf "Last output:\n%s\n" "$output"
+        fi
+        if [[ -n "${stderr:-}" ]]; then
+          printf "Last stderr: \n%s\n" "$stderr"
+        fi
+      fi  >> "$BATS_OUT"
 
       print_bats_out=1    
       status=1

test/bats.bats

@@ -1007,6 +1007,24 @@ END_OF_ERR_MSG
   [ ${#lines[@]} -eq 10 ]
 }
 
+@test "--print-output-on-failure also shows stderr (for run --separate-stderr)" {
+  run bats --print-output-on-failure --show-output-of-passing-tests "$FIXTURE_ROOT/print_output_on_failure_with_stderr.bats"
+  [ "${lines[0]}" == '1..3' ]
+  [ "${lines[1]}" == 'ok 1 no failure prints no output' ]
+  # ^ no output despite --show-output-of-passing-tests, because there is no failure
+  [ "${lines[2]}" == 'not ok 2 failure prints output' ]
+  [ "${lines[3]}" == "# (in test file $RELATIVE_FIXTURE_ROOT/print_output_on_failure_with_stderr.bats, line 7)" ]
+  [ "${lines[4]}" == "#   \`run -1 --separate-stderr bash -c 'echo \"fail hard\"; echo with stderr >&2'' failed, expected exit code 1, got 0" ]
+  [ "${lines[5]}" == '# Last output:' ]
+  [ "${lines[6]}" == '# fail hard' ]
+  [ "${lines[7]}" == '# Last stderr:' ]
+  [ "${lines[8]}" == '# with stderr' ]
+  [ "${lines[9]}" == 'not ok 3 empty output on failure' ]
+  [ "${lines[10]}" == "# (in test file $RELATIVE_FIXTURE_ROOT/print_output_on_failure_with_stderr.bats, line 11)" ]
+  [ "${lines[11]}" == "#   \`false' failed" ]
+  [ ${#lines[@]} -eq 12 ]
+}
+
 @test "--show-output-of-passing-tests works as expected" {
   bats_require_minimum_version 1.5.0
   run -0 bats --show-output-of-passing-tests "$FIXTURE_ROOT/show-output-of-passing-tests.bats"

test/fixtures/bats/print_output_on_failure_with_stderr.bats

@@ -0,0 +1,12 @@
+@test "no failure prints no output" {
+    run echo success
+}
+
+@test "failure prints output" {
+    bats_require_minimum_version 1.5.0
+    run -1 --separate-stderr bash -c 'echo "fail hard"; echo with stderr >&2'
+}
+
+@test "empty output on failure" {
+    false
+}