fix(go): restore error message visibility in formatter output

The formatter was suppressing critical error information by returning
empty strings for build failures, individual test failures, and most
FAIL output. This made debugging difficult when tests failed.

Changes:
- handleFail now shows build failures as "FAIL\t{package} [build failed]"
- handleFail now shows individual test failures as "FAIL\t{package}/{test}"
- handleBuildFail added to show "BUILD FAILED" instead of filtering
- handleOutput preserves all FAIL\t output instead of selective filtering

Tests updated to reflect new expected behavior that prioritizes error
visibility over minimal output.

Author: wizzomafizzo

reporters/go/internal/formatter/formatter.go

@@ -28,7 +28,7 @@ func (f *Formatter) initHandlers() {
 		"start":        returnEmpty,
 		"run":          returnEmpty,
 		"build-output": f.handleBuildOutput,
-		"build-fail":   returnEmpty,
+		"build-fail":   f.handleBuildFail,
 		"output":       f.handleOutput,
 		"pass":         f.handlePass,
 		"fail":         f.handleFail,
@@ -47,6 +47,13 @@ func (f *Formatter) handleBuildOutput(event parser.TestEvent) string {
 	return trimNewline(event.Output)
 }
 
+func (f *Formatter) handleBuildFail(event parser.TestEvent) string {
+	if event.Package != "" {
+		return fmt.Sprintf("BUILD FAILED\t%s", event.Package)
+	}
+	return "BUILD FAILED"
+}
+
 // handleOutput filters redundant output lines and preserves error messages.
 // Removes duplicate package summaries (we generate our own from pass/fail events)
 // and test execution markers while keeping actual test failures and error details.
@@ -63,11 +70,8 @@ func (f *Formatter) handleOutput(event parser.TestEvent) string {
 	case strings.HasPrefix(output, "ok  \t"):
 		return "" // Filtered - we generate from pass event
 	case strings.HasPrefix(output, "FAIL\t"):
-		// Keep compilation failures, filter test failures (generated from fail event)
-		if strings.Contains(output, "[setup failed]") {
-			return trimNewline(output)
-		}
-		return ""
+		// Keep all FAIL output to preserve error information
+		return trimNewline(output)
 	}
 
 	if event.Test != "" {
@@ -98,15 +102,19 @@ func (f *Formatter) handlePass(event parser.TestEvent) string {
 }
 
 // handleFail generates the "FAIL" summary line for failed package tests.
-// Avoids duplicate output for build failures which are already shown as "[setup failed]".
+// Shows build failures with package information for better error visibility.
 func (f *Formatter) handleFail(event parser.TestEvent) string {
 	if event.Package != "" && event.Test == "" {
 		if event.FailedBuild != "" {
-			return "" // Already shown as "FAIL ... [setup failed]" in output event
+			return fmt.Sprintf("FAIL\t%s [build failed]", event.Package)
 		}
 		return fmt.Sprintf("FAIL\t%s\t%.3fs", event.Package, event.Elapsed)
 	}
-	return "" // Filter individual test failures (details shown in output)
+	// Show individual test failure summaries for better error tracking
+	if event.Test != "" {
+		return fmt.Sprintf("FAIL\t%s/%s", event.Package, event.Test)
+	}
+	return ""
 }
 
 func (f *Formatter) handleUnknown(event parser.TestEvent) string {

reporters/go/internal/formatter/formatter_test.go

@@ -90,15 +90,16 @@ func TestFormatter(t *testing.T) {
 		}
 	})
 
-	t.Run("TestSkipPackageFailWithBuildFailure", func(t *testing.T) {
+	t.Run("TestShowPackageFailWithBuildFailure", func(t *testing.T) {
 		result := formatEvent(t, parser.TestEvent{
 			Action:      "fail",
 			Package:     "command-line-arguments",
 			Elapsed:     0,
 			FailedBuild: "github.com/non-existent/module",
 		})
-		if result != "" {
-			t.Fatalf("Expected build failure package fail to be filtered, got '%s'", result)
+		expected := "FAIL\tcommand-line-arguments [build failed]"
+		if result != expected {
+			t.Fatalf("Expected '%s', got '%s'", expected, result)
 		}
 	})
 
@@ -114,15 +115,16 @@ func TestFormatter(t *testing.T) {
 		}
 	})
 
-	t.Run("TestFilterTestLevelFailEvents", func(t *testing.T) {
+	t.Run("TestShowTestLevelFailEvents", func(t *testing.T) {
 		result := formatEvent(t, parser.TestEvent{
 			Action:  "fail",
 			Package: "command-line-arguments",
 			Test:    "TestCalculator",
 			Elapsed: 0.001,
 		})
-		if result != "" {
-			t.Fatalf("Expected test-level fail events to be filtered out, got '%s'", result)
+		expected := "FAIL\tcommand-line-arguments/TestCalculator"
+		if result != expected {
+			t.Fatalf("Expected '%s', got '%s'", expected, result)
 		}
 	})
 
@@ -174,14 +176,15 @@ func TestFormatter(t *testing.T) {
 		}
 	})
 
-	t.Run("TestFilterPackageFailOutput", func(t *testing.T) {
+	t.Run("TestShowPackageFailOutput", func(t *testing.T) {
 		result := formatEvent(t, parser.TestEvent{
 			Action:  "output",
 			Package: "example.com/pkg",
 			Output:  "FAIL\texample.com/pkg\t0.002s\n",
 		})
-		if result != "" {
-			t.Fatalf("Expected package FAIL output to be filtered out, got '%s'", result)
+		expected := "FAIL\texample.com/pkg\t0.002s"
+		if result != expected {
+			t.Fatalf("Expected '%s', got '%s'", expected, result)
 		}
 	})
 
@@ -208,10 +211,11 @@ func TestFormatter(t *testing.T) {
 		}
 	})
 
-	t.Run("TestFilterBuildFailEvents", func(t *testing.T) {
+	t.Run("TestShowBuildFailEvents", func(t *testing.T) {
 		result := formatEvent(t, parser.TestEvent{Action: "build-fail"})
-		if result != "" {
-			t.Fatalf("Expected build-fail events to be filtered out, got '%s'", result)
+		expected := "BUILD FAILED"
+		if result != expected {
+			t.Fatalf("Expected '%s', got '%s'", expected, result)
 		}
 	})