adds support for lines which are longer than the read buffer

shell/shell.go

@@ -163,12 +163,27 @@ func (e *Executor) Stop() error {
 func logOutput(wg *sync.WaitGroup, fp io.ReadCloser, out func(string, ...interface{})) {
 	defer wg.Done()
 	r := bufio.NewReader(fp)
+
+	var partial = false
+	var fullLine = ""
 	for {
-		line, _, err := r.ReadLine()
+		line, isPrefix, err := r.ReadLine()
 		if err != nil {
 			return
 		}
-		out("%s", string(line))
+
+		if !isPrefix && !partial {
+			out("%s", string(line))
+		} else if !isPrefix && partial {
+			out("%s", fullLine+string(line))
+			fullLine = ""
+			partial = false
+		} else if isPrefix && !partial {
+			fullLine = string(line)
+			partial = true
+		} else if isPrefix && partial {
+			fullLine += string(line)
+		}
 	}
 }
 

shell/shell_test.go

@@ -2,9 +2,11 @@ package shell
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"runtime"
 	"strings"
+	"syscall"
 	"testing"
 	"time"
 
@@ -196,3 +198,80 @@ func TestCaseInsensitivePath(t *testing.T) {
 		},
 	)
 }
+
+func generateLongLines() *string {
+	var sb strings.Builder
+
+	// Each line should be at least twice as large as the buffer used in `logOutput` (4k)
+	for i := 0; i < 10000; i++ {
+		sb.WriteRune(rune('A' + (i % 26)))
+	}
+
+	var longLine = sb.String()
+	var lines = strings.Join([]string{longLine, longLine, longLine, longLine}, "\n")
+
+	return &lines
+}
+
+func writeTempFile(s *string, f *os.File) error {
+	defer f.Close()
+	_, err := f.WriteString(*s)
+	if err != nil {
+		return err
+	}
+	err = f.Sync()
+	return err
+}
+
+func TestVeryLongLine(t *testing.T) {
+	f, err := ioutil.TempFile("", "testVeryLongLines")
+	if err != nil {
+		panic(err)
+	}
+	defer syscall.Unlink(f.Name())
+
+	shellTesting = true
+	var longLines = generateLongLines()
+
+	err = writeTempFile(longLines, f)
+	if err != nil {
+		panic(err)
+	}
+
+	var shells []string
+	var command string
+	if runtime.GOOS == "windows" {
+		shells = []string{
+			"modd",
+			"powershell",
+		}
+		command = fmt.Sprintf("type %s", f.Name())
+	} else {
+		shells = []string{
+			"sh",
+			"bash",
+			"modd",
+			"powershell",
+		}
+		command = fmt.Sprintf("cat %s", f.Name())
+	}
+	for _, sh := range shells {
+
+		longLineTest := cmdTest{
+			name:   "long-line-test",
+			cmd:    command,
+			logHas: *longLines,
+		}
+
+		t.Run(
+			fmt.Sprintf("%s/%s", sh, longLineTest.name),
+			func(t *testing.T) {
+				if _, err := CheckShell(sh); err != nil {
+					t.Skipf("skipping - %s", err)
+					return
+				}
+				testCmd(t, sh, longLineTest)
+			},
+		)
+	}
+}