first test case for tail

tests "-n -1"

need to abstract operations for multiple workflow

Makefile

@@ -1,4 +1,4 @@
 default:	test
 
 test:	*.go
-	GOPATH=~/as/logyard go test
+	GOPATH=~/as/logyard go test -v

tail.go

@@ -193,7 +193,7 @@ func (tail *Tail) tailFileSync() {
 							}
 							log.Printf("Successfully reopened %s", tail.Filename)
 							tail.reader = bufio.NewReaderSize(tail.file, tail.MaxLineSize)
-							changes = nil
+							changes = nil // XXX: how to kill changes' goroutine?
 							continue
 						} else {
 							log.Printf("Finishing because file has been moved/deleted: %s", tail.Filename)

tail_test.go

@@ -2,20 +2,88 @@ package tail
 
 import (
 	"testing"
+	"time"
+	"os"
+	"io/ioutil"
+	_ "fmt"
 )
 
+func init() {
+	err := os.RemoveAll(".test")
+	if err != nil {
+		panic(err)
+	}
+}
+
 // Test Config.MustExist
 func TestMissingFile(t *testing.T) {
-	_, err := TailFile("/no/such/file", Config{Follow: true, MustExist: true})
+	tail, err := TailFile("/no/such/file", Config{Follow: true, MustExist: true})
 	if err == nil {
 		t.Error("MustExist:true is violated")
+		tail.Stop()
 	}
-	_, err = TailFile("/no/such/file", Config{Follow: true, MustExist: false})
+	tail, err = TailFile("/no/such/file", Config{Follow: true, MustExist: false})
 	if err != nil {
 		t.Error("MustExist:false is violated")
 	}
+	tail.Stop()
 	_, err = TailFile("README.md", Config{Follow: true, MustExist: true})
 	if err != nil {
 		t.Error("MustExist:true on an existing file is violated")
 	}
+	tail.Stop()
+}
+
+func TestLocationMinusOne(t *testing.T) {
+	fix := NewFixture("simple")
+	err := ioutil.WriteFile(fix.path + "/test.txt", []byte("hello\nworld\n"), 0777)
+	if err != nil {
+		t.Error(err)
+	}
+	tail, err := TailFile(fix.path + "/test.txt", Config{Follow: true, Location: -1})
+	if err != nil {
+		t.Error(err)
+	}
+	go CompareTailWithLines(t, tail, []string{"hello", "world"})
+
+	// delete after 1 second, to give tail sufficient time to read all lines.
+	<-time.After(1 * time.Second)
+	err = os.Remove(fix.path + "/test.txt")
+	if err != nil {
+		t.Error(err)
+	}
+	tail.Stop()
+}
+
+type Fixture struct {
+	Name string
+	path string
+}
+
+func NewFixture(name string) Fixture {
+	fix := Fixture{name, ".test/" + name}
+	os.MkdirAll(fix.path, os.ModeTemporary | 0700)
+	return fix
+}
+
+func CompareTailWithLines(t *testing.T, tail *Tail, lines []string) {
+	for _, line := range lines {
+		tailedLine, ok := <-tail.Lines
+		if !ok {
+			t.Error("insufficient lines from tail")
+			return
+		}
+		if tailedLine == nil {
+			t.Errorf("tail.Lines returned nil; not possible")
+			return
+		}
+		if tailedLine.Text != line {
+			t.Errorf("mismatch; %s != %s", tailedLine.Text, line)
+			return
+		}
+	}
+	line, ok := <-tail.Lines
+	if ok {
+		t.Errorf("more content from tail: %s", line.Text)
+	}
 }