task: add optimized file-reader processor tests (task 376)

1 files changed, 146 insertions, 0 deletions

diff --git a/internal/io/fs/readfile_processor_test.go b/internal/io/fs/readfile_processor_test.go
new file mode 100644
index 0000000..2e3cb80
--- /dev/null
+++ b/internal/io/fs/readfile_processor_test.go
@@ -0,0 +1,146 @@
+package fs
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"reflect"
+	"testing"
+
+	"github.com/mimecast/dtail/internal/config"
+	"github.com/mimecast/dtail/internal/io/pool"
+	"github.com/mimecast/dtail/internal/lcontext"
+	"github.com/mimecast/dtail/internal/regex"
+)
+
+type captureProcessor struct {
+	lines      []string
+	errAtLine  int
+	processErr error
+	flushErr   error
+}
+
+func (p *captureProcessor) ProcessLine(lineContent *bytes.Buffer, _ uint64, _ string) error {
+	p.lines = append(p.lines, lineContent.String())
+	pool.RecycleBytesBuffer(lineContent)
+
+	if p.errAtLine > 0 && len(p.lines) == p.errAtLine {
+		return p.processErr
+	}
+	return nil
+}
+
+func (p *captureProcessor) Flush() error {
+	return p.flushErr
+}
+
+func (p *captureProcessor) Close() error {
+	return nil
+}
+
+func TestStartWithProcessorOptimizedReadsAllLines(t *testing.T) {
+	setServerConfigForProcessorTests(t)
+
+	filePath := writeProcessorTestFile(t, "alpha\nbeta\n")
+	re := regex.NewNoop()
+
+	cat := NewCatFile(filePath, "glob-id", make(chan string, 1))
+	processor := &captureProcessor{}
+
+	if err := cat.readFile.StartWithProcessorOptimized(
+		context.Background(),
+		lcontext.LContext{},
+		processor,
+		re,
+	); err != nil {
+		t.Fatalf("optimized reader start failed: %v", err)
+	}
+
+	want := []string{"alpha\n", "beta\n"}
+	if !reflect.DeepEqual(processor.lines, want) {
+		t.Fatalf("unexpected processed lines: got=%v want=%v", processor.lines, want)
+	}
+}
+
+func TestProcessorVariantsReturnOpenError(t *testing.T) {
+	setServerConfigForProcessorTests(t)
+
+	re := regex.NewNoop()
+	missingFile := filepath.Join(t.TempDir(), "missing.log")
+
+	tests := []struct {
+		name  string
+		start func(*readFile, context.Context, lcontext.LContext, *captureProcessor, regex.Regex) error
+	}{
+		{
+			name: "standard",
+			start: func(rf *readFile, ctx context.Context, ltx lcontext.LContext, p *captureProcessor, re regex.Regex) error {
+				return rf.StartWithProcessor(ctx, ltx, p, re)
+			},
+		},
+		{
+			name: "optimized",
+			start: func(rf *readFile, ctx context.Context, ltx lcontext.LContext, p *captureProcessor, re regex.Regex) error {
+				return rf.StartWithProcessorOptimized(ctx, ltx, p, re)
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cat := NewCatFile(missingFile, "glob-id", make(chan string, 1))
+			err := tt.start(&cat.readFile, context.Background(), lcontext.LContext{}, &captureProcessor{}, re)
+			if err == nil {
+				t.Fatalf("expected error for missing file")
+			}
+		})
+	}
+}
+
+func TestStartWithProcessorOptimizedPropagatesProcessError(t *testing.T) {
+	setServerConfigForProcessorTests(t)
+
+	filePath := writeProcessorTestFile(t, "alpha\nbeta\n")
+	re := regex.NewNoop()
+	expectedErr := errors.New("processor failure")
+
+	cat := NewCatFile(filePath, "glob-id", make(chan string, 1))
+	processor := &captureProcessor{
+		errAtLine:  1,
+		processErr: expectedErr,
+	}
+
+	err := cat.readFile.StartWithProcessorOptimized(
+		context.Background(),
+		lcontext.LContext{},
+		processor,
+		re,
+	)
+	if !errors.Is(err, expectedErr) {
+		t.Fatalf("expected process error %v, got %v", expectedErr, err)
+	}
+}
+
+func setServerConfigForProcessorTests(t *testing.T) {
+	t.Helper()
+
+	previousServer := config.Server
+	config.Server = &config.ServerConfig{
+		MaxLineLength: 1024 * 1024,
+	}
+	t.Cleanup(func() {
+		config.Server = previousServer
+	})
+}
+
+func writeProcessorTestFile(t *testing.T, content string) string {
+	t.Helper()
+
+	filePath := filepath.Join(t.TempDir(), "test.log")
+	if err := os.WriteFile(filePath, []byte(content), 0600); err != nil {
+		t.Fatalf("unable to write test file: %v", err)
+	}
+	return filePath
+}