Let plans wait for a plan to move and answer it as data (issue 229)

An agent following a rollout had plans answer once, in prose, and polled the
console with a curl loop of its own to be told a plan moved. plans now takes
wait (a plan's id), until (moved, tier or done) and bound, and answers when the
plan moves or the bound passes, saying which, with the plan as data and its
line as the output.

A call's one answer has to reach the console inside its thirty seconds, so
link.AnswersWithin lets a handler that waits on purpose hold its answer up to
LongestAnswer (25s) instead of AnswerWithin; the bound is at most 20s, and a
caller following a plan further asks again.

cmd/mesh-controller/plans_follow_test.go

@@ -0,0 +1,181 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// A plan as the store would answer it at each read: the reads are counted, and each answers the next.
+type planReads struct {
+	plans []inventory.Plan
+	n     int
+}
+
+func (r *planReads) read(context.Context) (inventory.Plan, error) {
+	p := r.plans[min(r.n, len(r.plans)-1)]
+	r.n++
+	return p, nil
+}
+
+func followedPlan(rev int64, state string, tier int) inventory.Plan {
+	return inventory.Plan{ID: "plan-1", Repository: "novox/x", Commit: "abc", State: state, Tier: tier,
+		Tiers: [][]string{{"a"}, {"b"}}, Revision: rev}
+}
+
+// **`plans` waits for a plan, and says what ended the wait** (novox/hq issue 229): an agent following a
+// rollout is told when the plan moved, reached its next tier or ended, or that the bound passed — in one
+// call, without a loop of its own.
+func TestAWaitForAPlanEndsWhenWhatItWaitsForHappens(t *testing.T) {
+	cases := []struct {
+		name  string
+		until string
+		reads []inventory.Plan
+		came  string
+		times int
+	}{
+		{"moved: any save", "moved", []inventory.Plan{
+			followedPlan(1, inventory.PlanBuilding, 0), followedPlan(1, inventory.PlanBuilding, 0),
+			followedPlan(2, inventory.PlanBuilding, 0)}, "moved", 3},
+		{"tier: a save inside the tier is not enough", "tier", []inventory.Plan{
+			followedPlan(1, inventory.PlanBuilding, 0), followedPlan(2, inventory.PlanBuilding, 0),
+			followedPlan(3, inventory.PlanRolling, 1)}, "tier", 3},
+		{"tier: a plan that ended has no next tier to wait for", "tier", []inventory.Plan{
+			followedPlan(1, inventory.PlanBuilding, 0), followedPlan(2, inventory.PlanFailed, 0)}, "done", 2},
+		{"done: a new tier is not the end", "done", []inventory.Plan{
+			followedPlan(1, inventory.PlanBuilding, 0), followedPlan(2, inventory.PlanRolling, 1),
+			followedPlan(3, inventory.PlanDone, 1)}, "done", 3},
+		{"done: a plan already ended answers at once", "done", []inventory.Plan{
+			followedPlan(4, inventory.PlanSuperseded, 1)}, "done", 1},
+		{"the bound passes", "moved", []inventory.Plan{followedPlan(1, inventory.PlanBuilding, 0)}, "bound", -1},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			r := &planReads{plans: c.reads}
+			p, came, err := waitOnPlan(context.Background(), r.read, c.until, 50*time.Millisecond, time.Millisecond)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if came != c.came {
+				t.Fatalf("the wait ended as %q, want %q", came, c.came)
+			}
+			if c.times > 0 && r.n != c.times {
+				t.Errorf("read the plan %d times, want %d: it answered before or after what it waited for", r.n, c.times)
+			}
+			if want := c.reads[min(r.n, len(c.reads))-1]; p.Revision != want.Revision {
+				t.Errorf("answered revision %d, not the plan as it was last read (%d)", p.Revision, want.Revision)
+			}
+		})
+	}
+}
+
+// What a wait is asked for is checked before anything is read: what it waits until, and a bound no longer than
+// a call is answered within.
+func TestAWaitIsRefusedWhatItCannotDo(t *testing.T) {
+	for _, bad := range []struct{ until, bound string }{{"landed", ""}, {"", "1h"}, {"", "-3s"}, {"", "soon"}} {
+		if _, _, err := planWaitAsked(bad.until, bad.bound); err == nil {
+			t.Errorf("until %q, bound %q was taken", bad.until, bad.bound)
+		}
+	}
+	until, bound, err := planWaitAsked("", "")
+	if err != nil || until != "moved" || bound != maxPlanWait {
+		t.Fatalf("the defaults are %q %s %v, want moved and %s", until, bound, err, maxPlanWait)
+	}
+	if _, bound, _ := planWaitAsked("tier", "12"); bound != 12*time.Second {
+		t.Errorf("a bare number is seconds; read %s", bound)
+	}
+}
+
+// **The answer is data, with its prose as a field beside it** (novox/hq issue 229): the verb's `answer` carries
+// the plan and what ended the wait, and its output is the line a person reads — never JSON inside a string.
+func TestAWaitForAPlanAnswersAsData(t *testing.T) {
+	p := followedPlan(7, inventory.PlanRolling, 1)
+	st := planStatuses([]inventory.Plan{p}, time.Now(), pauseView{}, tierBounds{})[0]
+	doc := planWaitedDoc(p, st, "tier", "tier", 3*time.Second, "rolling, tier 2 of 2")
+	stdout, _ := json.Marshal(doc)
+	a := answerOf([]string{"plans", "wait", "plan-1"}, stdout, "", true)
+	data, ok := a.Answer.(map[string]any)
+	if !ok {
+		t.Fatalf("the answer is not data: %v", a.Answer)
+	}
+	if data["came"] != "tier" || data["revision"] != float64(7) {
+		t.Errorf("the data does not say what ended the wait: %v", data)
+	}
+	if plan, _ := data["plan"].(map[string]any); plan["state"] != "rolling" || plan["tier"] != float64(1) {
+		t.Errorf("the data does not carry the plan: %v", data["plan"])
+	}
+	if _, text := data["text"]; text {
+		t.Errorf("the prose is in the data too: %v", data)
+	}
+	if strings.Contains(a.Output, "{") || !strings.Contains(a.Output, "plan-1") || !strings.Contains(a.Output, "tier") {
+		t.Errorf("the output is not the line a person reads: %q", a.Output)
+	}
+}
+
+// The verb composes the wait, and asks for a window as long as its bound.
+func TestThePlansVerbComposesAWait(t *testing.T) {
+	argv, err := argvFor("plans", map[string]any{"wait": "plan-1", "until": "done", "bound": "15s"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := strings.Join(argv, " "); got != "plans wait plan-1 --until done --bound 15s" {
+		t.Fatalf("composed %q", got)
+	}
+	if _, err := argvFor("plans", map[string]any{"until": "done"}); err == nil {
+		t.Error("until without wait was taken")
+	}
+	if _, err := argvFor("plans", map[string]any{"wait": "plan-1", "bound": "1h"}); err == nil {
+		t.Error("a bound past what a call can wait was taken")
+	}
+}
+
+// Live, with the store: `plans wait` run as the verb runs it answers when the plan reaches its next tier, as
+// data, and says the bound passed when nothing moved (novox/hq issue 229).
+func TestAPlanFollowedFromTheStoreAnswersWhenItMoves(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	now := time.Now().UTC()
+	walk := inventory.Plan{ID: "plan-229", Repository: "novox/mesh-catalog", Branch: "main", Commit: "c229c229",
+		Created: now, State: inventory.PlanBuilding, Tiers: [][]string{{"a"}, {"b"}},
+		Modules: map[string]*inventory.PlanModule{"a": {}, "b": {}}}
+	if err := open.inventory.SavePlan(ctx, &walk); err != nil {
+		t.Fatal(err)
+	}
+	moved := make(chan error, 1)
+	go func() {
+		time.Sleep(1500 * time.Millisecond)
+		p, err := open.inventory.PlanByID(ctx, walk.ID)
+		if err == nil {
+			p.Tier, p.State = 1, inventory.PlanRolling
+			err = open.inventory.SavePlan(ctx, &p)
+		}
+		moved <- err
+	}()
+	began := time.Now()
+	var got planWaited
+	out := printed(t, func() error {
+		return plansCommand(ctx, []string{"wait", walk.ID, "--until", "tier", "--bound", "15s"})
+	})
+	if err := <-moved; err != nil {
+		t.Fatal(err)
+	}
+	if err := json.Unmarshal([]byte(out), &got); err != nil {
+		t.Fatalf("plans wait did not answer data: %v: %q", err, out)
+	}
+	if got.Came != "tier" || got.Plan.Tier != 1 || got.Plan.State != inventory.PlanRolling {
+		t.Fatalf("the wait answered %+v", got)
+	}
+	if waited := time.Since(began); waited > 10*time.Second {
+		t.Errorf("it answered after %s, not when the plan moved", waited)
+	}
+	out = printed(t, func() error {
+		return plansCommand(ctx, []string{"wait", walk.ID, "--bound", "2"})
+	})
+	if err := json.Unmarshal([]byte(out), &got); err != nil || got.Came != "bound" || got.Until != "moved" {
+		t.Fatalf("a plan that did not move answered %+v (%v)", got, err)
+	}
+}