Add --max-fails flag

To terminate the test run when the number of failures is reached.

cmd/handler.go

@@ -16,6 +16,7 @@ type eventHandler struct {
 	formatter testjson.EventFormatter
 	err       io.Writer
 	jsonFile  io.WriteCloser
+	maxFails  int
 }
 
 func (h *eventHandler) Err(text string) error {
@@ -37,6 +38,10 @@ func (h *eventHandler) Event(event testjson.TestEvent, execution *testjson.Execu
 	if err != nil {
 		return errors.Wrap(err, "failed to format event")
 	}
+
+	if h.maxFails > 0 && len(execution.Failed()) >= h.maxFails {
+		return fmt.Errorf("ending test run because max failures was reached")
+	}
 	return nil
 }
 
@@ -59,6 +64,7 @@ func newEventHandler(opts *options) (*eventHandler, error) {
 	handler := &eventHandler{
 		formatter: formatter,
 		err:       opts.stderr,
+		maxFails:  opts.maxFails,
 	}
 	var err error
 	if opts.jsonFile != "" {

cmd/handler_test.go

@@ -2,6 +2,7 @@ package cmd
 
 import (
 	"bytes"
+	"io/ioutil"
 	"os"
 	"strings"
 	"testing"
@@ -71,3 +72,16 @@ func TestEventHandler_Event_WithMissingActionFail(t *testing.T) {
 	// of the formatter.
 	golden.Assert(t, errBuf.String(), "event-handler-missing-test-fail-expected")
 }
+
+func TestEventHandler_Event_MaxFails(t *testing.T) {
+	format := testjson.NewEventFormatter(ioutil.Discard, "testname")
+
+	source := golden.Get(t, "../../testjson/testdata/go-test-json.out")
+	cfg := testjson.ScanConfig{
+		Stdout:  bytes.NewReader(source),
+		Handler: &eventHandler{formatter: format, maxFails: 2},
+	}
+
+	_, err := testjson.ScanTestOutput(cfg)
+	assert.Error(t, err, "ending test run because max failures was reached")
+}

cmd/main.go

@@ -87,6 +87,8 @@ func setupFlags(name string) (*pflag.FlagSet, *options) {
 		"command to run after the tests have completed")
 	flags.BoolVar(&opts.watch, "watch", false,
 		"watch go files, and run tests when a file is modified")
+	flags.IntVar(&opts.maxFails, "max-fails", 0,
+		"end the test run after this number of failures")
 
 	flags.StringVar(&opts.junitFile, "junitfile",
 		lookEnvWithDefault("GOTESTSUM_JUNITFILE", ""),
@@ -163,6 +165,7 @@ type options struct {
 	rerunFailsOnlyRootCases      bool
 	packages                     []string
 	watch                        bool
+	maxFails                     int
 	version                      bool
 
 	// shims for testing

cmd/testdata/gotestsum-help-text

@@ -10,6 +10,7 @@ Flags:
       --junitfile string                            write a JUnit XML file
       --junitfile-testcase-classname field-format   format the testcase classname field as: full, relative, short (default full)
       --junitfile-testsuite-name field-format       format the testsuite name field as: full, relative, short (default full)
+      --max-fails int                               end the test run after this number of failures
       --no-color                                    disable color output (default true)
       --packages list                               space separated list of package to test
       --post-run-command command                    command to run after the tests have completed