test: pin the production receive limits, split the vacuous drain test, harden the lint-gate test (review of #55)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/uploads/intake_defaults_test.go

@@ -0,0 +1,31 @@
+package uploads_test
+
+// The limits production runs on are the DEFAULTS: nothing outside tests sets
+// MaxReceives or MaxReceivesPerUser. Pinned here with the literal numbers, so changing a
+// default is a visible decision (#47 review). With 4 receives, 20 queued and 1 running at
+// the 200 MiB cap, the spool needs ~5 GiB of the 6 Gi emptyDir (infra); raising any of
+// them or TAPIR_UPLOAD_MAX_BYTES must revisit that arithmetic.
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+
+	"git.d-ma.be/mathias/tapir/internal/uploads"
+)
+
+func TestNewIntake_DefaultsAllowTwoReceivesPerUserAndFourOverall(t *testing.T) {
+	r := newRig(t)
+	in := uploads.NewIntake(r.st, r.pr, r.sub, uploads.Limits{MaxBytes: 1024, MaxDuration: time.Hour}, r.tmp)
+	startSlowReceive(t, r, in, "a", 1)
+	startSlowReceive(t, r, in, "a", 2)
+
+	_, err := in.Accept(context.Background(), "a", "t", strings.NewReader("x"))
+	requireBusy(t, err) // a third body from one user
+
+	startSlowReceive(t, r, in, "b", 3)
+	startSlowReceive(t, r, in, "b", 4)
+	_, err = in.Accept(context.Background(), "c", "t", strings.NewReader("x"))
+	requireBusy(t, err) // a fifth body overall
+}