Handle displaying empty files

And introduce a unit test!

m/reader.go

@@ -28,6 +28,7 @@ type Lines struct {
 
 // NewReaderFromStream creates a new stream reader
 func NewReaderFromStream(reader io.Reader) (*_Reader, error) {
+	// FIXME: Close the stream when done reading it?
 	scanner := bufio.NewScanner(reader)
 	var lines []string
 	for scanner.Scan() {
@@ -49,7 +50,9 @@ func NewReaderFromFilename(filename string) (*_Reader, error) {
 		return nil, err
 	}
 
-	return NewReaderFromStream(stream)
+	reader, err := NewReaderFromStream(stream)
+	reader.name = filename
+	return reader, err
 }
 
 func (r *_Reader) LineCount() int {
@@ -61,6 +64,15 @@ func (r *_Reader) GetLines(firstLineOneBased int, wantedLineCount int) *Lines {
 		firstLineOneBased = 1
 	}
 
+	if len(r.lines) == 0 {
+		return &Lines{
+			lines:             r.lines,
+
+			// FIXME: What line number should we set here?
+			firstLineOneBased: firstLineOneBased,
+		}
+	}
+
 	firstLineZeroBased := firstLineOneBased - 1
 	lastLineZeroBased := firstLineZeroBased + wantedLineCount - 1
 

m/reader_test.go

@@ -0,0 +1,43 @@
+package m
+
+import "testing"
+
+func _TestGetLines(t *testing.T, reader *_Reader) {
+	t.Logf("Testing file: %s...", reader.name)
+
+	lines := reader.GetLines(1, 10)
+	if len(lines.lines) > 10 {
+		t.Errorf("Asked for 10 lines, got too many: %d", len(lines.lines))
+	}
+
+	if len(lines.lines) < 10 {
+		// No good plan for how to test short files more
+		return
+	}
+
+	// Test clipping at the end
+	lineCount := reader.LineCount()
+	lines = reader.GetLines(lineCount, 10)
+	if len(lines.lines) != 10 {
+		t.Errorf("Asked for 10 lines, got too few: %d", len(lines.lines))
+		return
+	}
+	if lines.firstLineOneBased != lineCount - 9 {
+		t.Errorf("Expected last line to be %d, was %d", lineCount - 9, lines.firstLineOneBased)
+		return
+	}
+}
+
+func TestGetLines(t *testing.T) {
+	// FIXME: List all files in ../sample-files
+	files := []string {"../sample-files/empty.txt"}
+	for _, file := range files {
+		reader, e := NewReaderFromFilename(file)
+		if e != nil {
+			t.Errorf("Error opening file <%s>: %s", file, e.Error())
+			continue
+		}
+
+		_TestGetLines(t, reader)
+	}
+}

moar.sh

@@ -4,7 +4,7 @@ set -e -o pipefail
 
 rm -f moar
 
-go test 1>&2
+go test github.com/walles/moar/m 1>&2
 
 go build 1>&2
 

test.sh

@@ -7,7 +7,7 @@ GOOS=linux GOARCH=386 go build
 GOOS=darwin GOARCH=amd64 go build
 
 # Unit tests first...
-go test
+go test github.com/walles/moar/m
 
 # ... then Verify sending the output to a file
 go build