Implement error reporter format for GitHub Actions

testjson/format.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
+	"regexp"
 	"sort"
 	"strings"
 
@@ -454,6 +456,23 @@ func NewEventFormatter(out io.Writer, format string, formatOpts FormatOptions) E
 	}
 }
 
+type githubActionsErrorPatterns struct {
+	fileLine   *regexp.Regexp
+	panicStack *regexp.Regexp
+	panicLine  *regexp.Regexp
+}
+
+func newGitHubActionsErrorPatterns() githubActionsErrorPatterns {
+	return githubActionsErrorPatterns{
+		// Matches "    filename.go:123:" style lines emitted by go test failures
+		fileLine: regexp.MustCompile(`^\s+([a-zA-Z0-9_\-./]+\.go):(\d+):`),
+		// Matches stack frames emitted in Go panic traces
+		panicStack: regexp.MustCompile(`^\t(.+\.go):(\d+) \+0x`),
+		// Matches canonical panic lines such as "panic: runtime error: ..."
+		panicLine: regexp.MustCompile(`^panic:\s*`),
+	}
+}
+
 func githubActionsFormat(out io.Writer) EventFormatter {
 	buf := bufio.NewWriter(out)
 
@@ -463,6 +482,8 @@ func githubActionsFormat(out io.Writer) EventFormatter {
 	}
 	output := map[name][]string{}
 
+	patterns := newGitHubActionsErrorPatterns()
+
 	return eventFormatterFunc(func(event TestEvent, exec *Execution) error {
 		key := name{Package: event.Package, Test: event.Test}
 
@@ -476,6 +497,11 @@ func githubActionsFormat(out io.Writer) EventFormatter {
 
 		// test case end event
 		if event.Test != "" && event.Action.IsTerminal() {
+			// Emit error annotation for failed tests
+			if event.Action == ActionFail {
+				writeGitHubActionsError(buf, event, output[key], patterns)
+			}
+
 			if len(output[key]) > 0 {
 				buf.WriteString("::group::")
 			} else {
@@ -513,3 +539,86 @@ func githubActionsFormat(out io.Writer) EventFormatter {
 		return buf.Flush()
 	})
 }
+
+// writeGitHubActionsError parses test output and emits GitHub Actions error annotations
+func writeGitHubActionsError(
+	buf *bufio.Writer, event TestEvent, outputLines []string, patterns githubActionsErrorPatterns,
+) {
+	sanitize := func(s string) string {
+		// Percent must be escaped first
+		s = strings.ReplaceAll(s, "%", "%25")
+		// Escape newlines and carriage returns
+		s = strings.ReplaceAll(s, "\r", "%0D")
+		s = strings.ReplaceAll(s, "\n", "%0A")
+		return s
+	}
+
+	// Check if this is a panic by looking for panic: in the output
+	var isPanic bool
+	var panicMessage strings.Builder
+	for _, outputLine := range outputLines {
+		trimmed := strings.TrimSpace(outputLine)
+		if patterns.panicLine.MatchString(trimmed) {
+			isPanic = true
+			panicMessage.WriteString(trimmed)
+			panicMessage.WriteString(" ")
+		}
+	}
+
+	if isPanic {
+		// For panics, emit a single annotation with the panic location
+		var file string
+		var line string
+
+		// Look for the test file in the stack trace
+		// Prefer _test.go files over other files (like testing.go or runtime files)
+		for _, outputLine := range outputLines {
+			if matches := patterns.panicStack.FindStringSubmatch(outputLine); len(matches) == 3 {
+				stackFile := filepath.Base(matches[1])
+				stackLine := matches[2]
+				isTestFile := strings.HasSuffix(stackFile, "_test.go")
+
+				if file == "" || isTestFile {
+					file = stackFile
+					line = stackLine
+
+					if isTestFile {
+						break
+					}
+				}
+			}
+		}
+
+		message := strings.TrimSpace(panicMessage.String())
+		if message == "" {
+			message = "Test panicked"
+		}
+
+		if file != "" && line != "" {
+			fmt.Fprintf(buf, "::error file=%s,line=%s,title=%s::%s\n",
+				sanitize(file), line, sanitize(event.Test), sanitize(message))
+		} else {
+			fmt.Fprintf(buf, "::error title=%s::%s\n", sanitize(event.Test), sanitize(message))
+		}
+	} else {
+		// For regular test failures, emit one annotation per error line
+		for _, outputLine := range outputLines {
+			if matches := patterns.fileLine.FindStringSubmatch(outputLine); len(matches) == 3 {
+				file := matches[1]
+				line := matches[2]
+
+				parts := strings.SplitN(outputLine, ":", 3)
+				var message string
+				if len(parts) >= 3 {
+					message = strings.TrimSpace(parts[2])
+				}
+				if message == "" {
+					message = "Test failed"
+				}
+
+				fmt.Fprintf(buf, "::error file=%s,line=%s,title=%s::%s\n",
+					sanitize(file), line, sanitize(event.Test), sanitize(message))
+			}
+		}
+	}
+}

testjson/github_actions_format_test.go

@@ -0,0 +1,65 @@
+package testjson
+
+import (
+	"bufio"
+	"bytes"
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func flushGitHubActionsBuffer(t *testing.T, buf *bufio.Writer, out *bytes.Buffer) string {
+	t.Helper()
+	assert.NilError(t, buf.Flush())
+	return out.String()
+}
+
+func TestWriteGitHubActionsError_FailureAnnotations(t *testing.T) {
+	out := new(bytes.Buffer)
+	writer := bufio.NewWriter(out)
+
+	event := TestEvent{Test: "pkg.TestFailure"}
+	lines := []string{"\tfailure_test.go:42: something went wrong"}
+
+	writeGitHubActionsError(writer, event, lines, newGitHubActionsErrorPatterns())
+
+	assert.Equal(t,
+		flushGitHubActionsBuffer(t, writer, out),
+		"::error file=failure_test.go,line=42,title=pkg.TestFailure::something went wrong\n",
+	)
+}
+
+func TestWriteGitHubActionsError_PanicPrefersTestFile(t *testing.T) {
+	out := new(bytes.Buffer)
+	writer := bufio.NewWriter(out)
+
+	event := TestEvent{Test: "pkg.TestPanics"}
+	lines := []string{
+		"panic: runtime error: index out of range",
+		"\t/usr/local/go/src/runtime/panic.go:88 +0x123",
+		"\t/home/user/project/example_test.go:45 +0x456",
+		"\t/home/user/project/example.go:12 +0x222",
+	}
+
+	writeGitHubActionsError(writer, event, lines, newGitHubActionsErrorPatterns())
+
+	assert.Equal(t,
+		flushGitHubActionsBuffer(t, writer, out),
+		"::error file=example_test.go,line=45,title=pkg.TestPanics::panic: runtime error: index out of range\n",
+	)
+}
+
+func TestWriteGitHubActionsError_PanicRequiresStrictMatch(t *testing.T) {
+	out := new(bytes.Buffer)
+	writer := bufio.NewWriter(out)
+
+	event := TestEvent{Test: "pkg.TestLogsPanicWord"}
+	lines := []string{"\tfailure_test.go:12: panic: not a real panic"}
+
+	writeGitHubActionsError(writer, event, lines, newGitHubActionsErrorPatterns())
+
+	assert.Equal(t,
+		flushGitHubActionsBuffer(t, writer, out),
+		"::error file=failure_test.go,line=12,title=pkg.TestLogsPanicWord::panic: not a real panic\n",
+	)
+}

testjson/testdata/format/github-actions.out

@@ -74,35 +74,42 @@ this is a Print
 this is stderr
 
 ::endgroup::
+::error file=fails_test.go,line=50,title=TestNestedParallelFailures/a::failed sub a
 ::group::FAIL testjson/internal/parallelfails.TestNestedParallelFailures/a (0.00s)
     fails_test.go:50: failed sub a
     --- FAIL: TestNestedParallelFailures/a (0.00s)
 
 ::endgroup::
+::error file=fails_test.go,line=50,title=TestNestedParallelFailures/d::failed sub d
 ::group::FAIL testjson/internal/parallelfails.TestNestedParallelFailures/d (0.00s)
     fails_test.go:50: failed sub d
     --- FAIL: TestNestedParallelFailures/d (0.00s)
 
 ::endgroup::
+::error file=fails_test.go,line=50,title=TestNestedParallelFailures/c::failed sub c
 ::group::FAIL testjson/internal/parallelfails.TestNestedParallelFailures/c (0.00s)
     fails_test.go:50: failed sub c
     --- FAIL: TestNestedParallelFailures/c (0.00s)
 
 ::endgroup::
+::error file=fails_test.go,line=50,title=TestNestedParallelFailures/b::failed sub b
 ::group::FAIL testjson/internal/parallelfails.TestNestedParallelFailures/b (0.00s)
     fails_test.go:50: failed sub b
     --- FAIL: TestNestedParallelFailures/b (0.00s)
 
 ::endgroup::
   FAIL testjson/internal/parallelfails.TestNestedParallelFailures (0.00s)
+::error file=fails_test.go,line=29,title=TestParallelTheFirst::failed the first
 ::group::FAIL testjson/internal/parallelfails.TestParallelTheFirst (0.01s)
     fails_test.go:29: failed the first
 
 ::endgroup::
+::error file=fails_test.go,line=41,title=TestParallelTheThird::failed the third
 ::group::FAIL testjson/internal/parallelfails.TestParallelTheThird (0.00s)
     fails_test.go:41: failed the third
 
 ::endgroup::
+::error file=fails_test.go,line=35,title=TestParallelTheSecond::failed the second
 ::group::FAIL testjson/internal/parallelfails.TestParallelTheSecond (0.01s)
     fails_test.go:35: failed the second
 
@@ -126,6 +133,7 @@ this is a Print
     fails_test.go:30: the skip message
 
 ::endgroup::
+::error file=fails_test.go,line=34,title=TestFailed::this failed
 ::group::FAIL testjson/internal/withfails.TestFailed (0.00s)
     fails_test.go:34: this failed
 
@@ -134,6 +142,7 @@ this is a Print
 this is stderr
 
 ::endgroup::
+::error file=fails_test.go,line=43,title=TestFailedWithStderr::also failed
 ::group::FAIL testjson/internal/withfails.TestFailedWithStderr (0.00s)
 this is stderr
     fails_test.go:43: also failed
@@ -155,6 +164,7 @@ this is stderr
     --- PASS: TestNestedWithFailure/b (0.00s)
 
 ::endgroup::
+::error file=fails_test.go,line=65,title=TestNestedWithFailure/c::failed
 ::group::FAIL testjson/internal/withfails.TestNestedWithFailure/c (0.00s)
     fails_test.go:65: failed
     --- FAIL: TestNestedWithFailure/c (0.00s)