main_test.go

package main

import (
	"bytes"
	"errors"
	"os"
	"path/filepath"
	"testing"
)

const dirFlag = "-dir"

// writeProjects creates dir/<project>/<session>.jsonl with the given lines and
// returns dir.
func writeProjects(t *testing.T, lines string) string {
	t.Helper()
	dir := t.TempDir()
	project := filepath.Join(dir, "project-a")
	if err := os.Mkdir(project, 0o750); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(project, "s1.jsonl"), []byte(lines), 0o600); err != nil {
		t.Fatal(err)
	}
	return dir
}

func TestRun(t *testing.T) {
	// 23:50 and 00:05 in Tokyo: 10 minutes on Oct 8 and 5 on Oct 9.
	dir := writeProjects(t, `{"type":"user","timestamp":"2026-10-08T14:50:00Z","sessionId":"s1"}
{"type":"assistant","timestamp":"2026-10-08T15:05:00Z","sessionId":"s1"}
`)
	var out bytes.Buffer

	if err := run([]string{dirFlag, dir}, &out); err != nil {
		t.Fatal(err)
	}
	want := "2026-10-08\t10\n2026-10-09\t5\n"
	if got := out.String(); got != want {
		t.Errorf("output = %q, want %q", got, want)
	}
}

func TestRunFlags(t *testing.T) {
	// A 5m40s gap from 00:00 Tokyo time (still Oct 8 in UTC), printed as 5
	// because minutes are rounded down; then a 12-minute gap, which -break 10m
	// excludes and the 15m default would count.
	dir := writeProjects(t, `{"type":"user","timestamp":"2026-10-08T15:00:00Z","sessionId":"s1"}
{"type":"assistant","timestamp":"2026-10-08T15:05:40Z","sessionId":"s1"}
{"type":"user","timestamp":"2026-10-08T15:17:40Z","sessionId":"s1"}
`)
	var out bytes.Buffer

	if err := run([]string{dirFlag, dir, "-break", "10m", "-tz", "UTC"}, &out); err != nil {
		t.Fatal(err)
	}
	want := "2026-10-08\t5\n"
	if got := out.String(); got != want {
		t.Errorf("output = %q, want %q", got, want)
	}
}

func TestRunHelp(t *testing.T) {
	if err := run([]string{"-h"}, &bytes.Buffer{}); err != nil {
		t.Errorf("run(-h) error = %v, want nil", err)
	}
}

func TestRunErrors(t *testing.T) {
	tests := []struct {
		name string
		args []string
	}{
		{name: "unknown flag", args: []string{"-nope"}},
		{name: "unknown time zone", args: []string{"-tz", "Nowhere/City"}},
		{name: "missing directory", args: []string{dirFlag, filepath.Join(t.TempDir(), "missing")}},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if err := run(tt.args, &bytes.Buffer{}); err == nil {
				t.Error("run() error = nil, want an error")
			}
		})
	}
}

var errWrite = errors.New("write failed")

type failingWriter struct{}

func (failingWriter) Write([]byte) (int, error) { return 0, errWrite }

func TestRunWriteError(t *testing.T) {
	dir := writeProjects(t, `{"type":"user","timestamp":"2026-10-08T10:00:00Z","sessionId":"s1"}
{"type":"assistant","timestamp":"2026-10-08T10:05:00Z","sessionId":"s1"}
`)

	err := run([]string{dirFlag, dir}, failingWriter{})
	if !errors.Is(err, errWrite) {
		t.Errorf("run() error = %v, want it to wrap %v", err, errWrite)
	}
}