1 files changed, 260 insertions, 0 deletions
diff --git a/cmds/train_test.go b/cmds/train_test.go
new file mode 100644
index 0000000..5a2ecee
--- /dev/null
+++ b/cmds/train_test.go
@@ -0,0 +1,260 @@
+// Tests for `fluxrec train`: reproducibility, metrics, and model envelope
+// consumption by the `score` command.
+package cmds
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"fluxrec/core"
+)
+
+// syntheticLabels builds a labels.jsonl file interleaving positives and
+// negatives across time (so the newest validation window contains both
+// classes), with varied feed titles so the feed-identity token is exercised.
+// Timestamps are sequential by position: oldest first, newest last, so the
+// time split's "newest val-frac" is a clean tail slice with mixed labels.
+func syntheticLabels(t *testing.T, path string, nPos, nNeg int) {
+	t.Helper()
+	now := time.Now().UTC()
+	total := nPos + nNeg
+	rows := make([]core.LabelRow, total)
+	posTitles := []string{
+		"New evidence on the rate of productivity growth in services",
+		"Why headline-only models are fine actually, a reanalysis",
+		"Field notes from sixty days of careful RSS triage at home",
+		"The economics of attention and the case for reading slower",
+		"A long retrospective on building small personal recommendation tools",
+		"Decade-scale trends in academic publishing, a meta-review",
+		"How I learned to stop worrying and love the title-only classifier",
+		"Notes on serendipity, exploration budgets, and ranked recall",
+		"Reflections on a year of minimal-information inference methods",
+		"The quiet resurgence of logistic regression in small data settings",
+	}
+	negTitles := []string{
+		"Roundup of this week's product launches and minor updates",
+		"Local weather forecast for the coming weekend and beyond",
+		"Five ways to organize your desk for slightly better focus",
+		"Celebrity interview about their new streaming television show",
+		"Sports scores and highlights from last night's important games",
+		"Markets close mostly unchanged as investors await fresh data",
+		"Travel deals for the autumn season across several destinations",
+		"Cooking tips for weeknight dinners under thirty minutes flat",
+		"Opinion piece on city traffic and the eternal parking problem",
+		"Best of the app store this month, ten small utilities reviewed",
+	}
+	feeds := []string{"Marginal Revolution", "ACM Tech News", "Some Other Blog", "Hacker News", "The Atlantic"}
+	pi, ni := 0, 0
+	for i := 0; i < total; i++ {
+		// Place a positive on even indices while positives remain, so
+		// labels interleave across the whole time range including the tail.
+		label := core.LabelNeg
+		title := ""
+		if i%2 == 0 && pi < nPos {
+			label, title = core.LabelPos, posTitles[pi%len(posTitles)]
+			pi++
+		} else {
+			label, title = core.LabelNeg, negTitles[ni%len(negTitles)]
+			ni++
+		}
+		rows[i] = core.LabelRow{
+			EntryID: int64(i + 1), URL: "https://example.com/" + label + "/" + itoa(i),
+			Title: title, FeedID: int64(i%len(feeds) + 1), FeedTitle: feeds[i%len(feeds)],
+			Label: label, CapturedAt: now.Add(-time.Duration(total-i) * 24 * time.Hour),
+		}
+	}
+	if err := core.AppendLabels(path, rows); err != nil {
+		t.Fatalf("AppendLabels: %v", err)
+	}
+}
+
+func itoa(i int) string {
+	b := []byte{}
+	if i == 0 {
+		return "0"
+	}
+	for i > 0 {
+		b = append([]byte{byte('0' + i%10)}, b...)
+		i /= 10
+	}
+	return string(b)
+}
+
+func runTrain(t *testing.T, labelsPath, dir string) (modelPath, reportPath string) {
+	t.Helper()
+	modelPath = filepath.Join(dir, "model.json")
+	reportPath = filepath.Join(dir, "report.json")
+	cmd := &TrainCommand{}
+	if err := cmd.Init([]string{labelsPath, "--model-out", modelPath, "--report-out", reportPath, "--val-frac", "0.3"}); err != nil {
+		t.Fatalf("Init: %v", err)
+	}
+	var out bytes.Buffer
+	if err := cmd.Run(nil, &out); err != nil {
+		t.Fatalf("Run: %v\nstdout: %s", err, out.String())
+	}
+	return
+}
+
+// B4: same labels → byte-identical model.json (seeds make training deterministic).
+func TestTrainReproducible(t *testing.T) {
+	dir := t.TempDir()
+	labelsPath := filepath.Join(dir, "labels.jsonl")
+	// Enough rows that a 0.3 val split has >=5 positives in val.
+	syntheticLabels(t, labelsPath, 50, 50)
+
+	m1, r1 := runTrain(t, labelsPath, dir)
+	body1, err := os.ReadFile(m1)
+	if err != nil {
+		t.Fatalf("read model1: %v", err)
+	}
+	report1, err := os.ReadFile(r1)
+	if err != nil {
+		t.Fatalf("read report1: %v", err)
+	}
+
+	// Second train to a second pair of paths.
+	dir2 := t.TempDir()
+	m2, r2 := runTrain(t, labelsPath, dir2)
+	body2, err := os.ReadFile(m2)
+	if err != nil {
+		t.Fatalf("read model2: %v", err)
+	}
+	report2, err := os.ReadFile(r2)
+	if err != nil {
+		t.Fatalf("read report2: %v", err)
+	}
+
+	// Strip CreatedAt (wall clock) before comparing models — the rest must
+	// be byte-identical. Compare reports fully.
+	var env1, env2 core.ModelEnvelope
+	if err := json.Unmarshal(body1, &env1); err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal(body2, &env2); err != nil {
+		t.Fatal(err)
+	}
+	env1.CreatedAt = time.Time{}
+	env2.CreatedAt = time.Time{}
+	c1, _ := json.Marshal(env1)
+	c2, _ := json.Marshal(env2)
+	if string(c1) != string(c2) {
+		t.Fatal("model not reproducible: weights/vocab differ across runs with same labels")
+	}
+	if string(report1) != string(report2) {
+		t.Fatal("report not reproducible: differs across runs with same labels")
+	}
+}
+
+// B5: report.json parses and precision@15 is a valid probability.
+func TestTrainReportValid(t *testing.T) {
+	dir := t.TempDir()
+	labelsPath := filepath.Join(dir, "labels.jsonl")
+	syntheticLabels(t, labelsPath, 50, 50)
+
+	modelPath, reportPath := runTrain(t, labelsPath, dir)
+
+	var report trainReport
+	body, err := os.ReadFile(reportPath)
+	if err != nil {
+		t.Fatalf("read report: %v", err)
+	}
+	if err := json.Unmarshal(body, &report); err != nil {
+		t.Fatalf("report unparseable: %v", err)
+	}
+	if report.PrecisionAt15 < 0 || report.PrecisionAt15 > 1 {
+		t.Errorf("precision@15 = %v, want in [0,1]", report.PrecisionAt15)
+	}
+	if report.VocabSize <= 0 {
+		t.Errorf("vocab size = %d, want > 0", report.VocabSize)
+	}
+	if report.TrainPos == 0 || report.TrainNeg == 0 {
+		t.Errorf("train should have both classes: pos=%d neg=%d", report.TrainPos, report.TrainNeg)
+	}
+	if report.ValPos < 5 {
+		t.Errorf("val pos = %d, guard should have required >=5", report.ValPos)
+	}
+	if report.Seed != trainSeed {
+		t.Errorf("seed = %d, want %d", report.Seed, trainSeed)
+	}
+
+	// Model file exists and has non-empty vocab + weights.
+	mbody, err := os.ReadFile(modelPath)
+	if err != nil {
+		t.Fatalf("read model: %v", err)
+	}
+	var model core.ModelEnvelope
+	if err := json.Unmarshal(mbody, &model); err != nil {
+		t.Fatalf("model unparseable: %v", err)
+	}
+	if len(model.Weights) == 0 || len(model.OrderedVocab) == 0 {
+		t.Fatal("model missing weights or vocab")
+	}
+}
+
+// B6: the produced model.json is consumable by the score command's loader
+// (same ModelEnvelope type). Round-trips through CreateVectorizerFromModel.
+func TestTrainModelConsumedByScore(t *testing.T) {
+	dir := t.TempDir()
+	labelsPath := filepath.Join(dir, "labels.jsonl")
+	syntheticLabels(t, labelsPath, 50, 50)
+
+	modelPath, _ := runTrain(t, labelsPath, dir)
+
+	model, err := loadModel(modelPath) // same loader the score command uses
+	if err != nil {
+		t.Fatalf("loadModel (score's loader): %v", err)
+	}
+	vec := core.CreateVectorizerFromModel(model)
+	title := "A long retrospective on building small personal recommendation tools"
+	out := vec.Transform([]string{core.ScoringText(title, "Marginal Revolution")})
+	score, err := core.PredictScore(out[0], model.Weights)
+	if err != nil {
+		t.Fatalf("PredictScore: %v", err)
+	}
+	if score < 0 || score > 1 {
+		t.Errorf("score = %v, want in [0,1]", score)
+	}
+}
+
+// Guard: too few validation positives must error loudly.
+func TestTrainGuardFewValPositives(t *testing.T) {
+	dir := t.TempDir()
+	labelsPath := filepath.Join(dir, "labels.jsonl")
+	// 5 positives total, val-frac 0.3 → 1-2 val positives < 5.
+	syntheticLabels(t, labelsPath, 5, 20)
+
+	cmd := &TrainCommand{}
+	if err := cmd.Init([]string{labelsPath, "--val-frac", "0.3", "--model-out",
+		filepath.Join(dir, "m.json"), "--report-out", filepath.Join(dir, "r.json")}); err != nil {
+		t.Fatalf("Init: %v", err)
+	}
+	var out bytes.Buffer
+	err := cmd.Run(nil, &out)
+	if err == nil {
+		t.Fatal("expected error for <5 validation positives, got nil")
+	}
+	if !strings.Contains(err.Error(), "positives in validation") {
+		t.Errorf("error should mention validation positives: %v", err)
+	}
+}
+
+// Guard: empty labels file errors.
+func TestTrainEmptyLabels(t *testing.T) {
+	dir := t.TempDir()
+	labelsPath := filepath.Join(dir, "empty.jsonl")
+	if err := os.WriteFile(labelsPath, []byte{}, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	cmd := &TrainCommand{}
+	if err := cmd.Init([]string{labelsPath}); err != nil {
+		t.Fatalf("Init: %v", err)
+	}
+	if err := cmd.Run(nil, &bytes.Buffer{}); err == nil {
+		t.Fatal("expected error for empty labels")
+	}
+}