mesh-controller/cmd/mesh-controller/status_test.go

package main

import (
	"encoding/json"
	"strings"
	"testing"
)

// **One machine's failure must never take the answer away from a reader asking about the others.**
//
// A blocked machine is not on the private network, and a mesh whose hub is that machine has no hub
// — which came back through the reading as a refusal, so `status` printed nothing at all and
// `status --json` emitted multi-line prose on stderr and not one byte of JSON. A machine-readable
// interface that stops being machine-readable exactly when something is wrong is one nobody can
// build an alarm on.
func TestOneBlockedMachineDoesNotDestroyTheWholeDocument(t *testing.T) {
	open := aMesh(t)
	ctx := t.Context()

	// Break the hub, using nothing but the command a person has.
	one, two := rivals()
	register(t, open, one)
	register(t, open, two)
	for _, m := range []string{"rival-one", "rival-two"} {
		if _, err := assign(ctx, open, "anchor", m); err != nil && m == "rival-one" {
			t.Fatal(err)
		}
	}

	asked, err := theThreeQuestions(ctx, open)
	if err != nil {
		t.Fatalf("one blocked machine made the whole mesh unreadable: %v", err)
	}
	body, err := statusAsJSON(asked)
	if err != nil {
		t.Fatal(err)
	}
	var parsed map[string]any
	if err := json.Unmarshal(body, &parsed); err != nil {
		t.Fatalf("what a script would read is not JSON: %v\n%s", err, body)
	}

	// The failure is in the document, as data, on the machine it belongs to.
	unresolved, _ := parsed["unresolved"].([]any)
	if len(unresolved) == 0 {
		t.Fatalf("a machine that cannot be worked out is absent from the document:\n%s", body)
	}
	var found bool
	for _, row := range unresolved {
		entry, _ := row.(map[string]any)
		if entry["node"] != "anchor" {
			continue
		}
		found = true
		problem, _ := entry["problem"].(string)
		if !strings.Contains(problem, "the-seat") {
			t.Errorf("the machine's problem is not its own words: %q", problem)
		}
	}
	if !found {
		t.Fatalf("the blocked machine is not the one named:\n%s", body)
	}
	// And the mesh is still counted, so a reader can tell "none blocked" from "none at all".
	if parsed["machines"] != float64(2) {
		t.Errorf("the rest of the document did not survive: %v", parsed["machines"])
	}
}

// A well mesh carries the field as an empty list, not as nothing: a reader distinguishing "none
// blocked" from "this field is missing" would have to handle both, and null is the one that gets
// forgotten.
func TestAWellMeshCarriesAnEmptyUnresolvedList(t *testing.T) {
	open := aMesh(t)
	asked, err := theThreeQuestions(t.Context(), open)
	if err != nil {
		t.Fatal(err)
	}
	body, err := statusAsJSON(asked)
	if err != nil {
		t.Fatal(err)
	}
	var parsed map[string]any
	if err := json.Unmarshal(body, &parsed); err != nil {
		t.Fatal(err)
	}
	list, ok := parsed["unresolved"].([]any)
	if !ok {
		t.Fatalf("\"unresolved\" is %T, not a list:\n%s", parsed["unresolved"], body)
	}
	if len(list) != 0 {
		t.Fatalf("a well mesh reports blocked machines: %v", list)
	}
	if _, said := parsed["network"]; said {
		t.Errorf("a well mesh says the network could not be computed: %v", parsed["network"])
	}
}

// And the page says it too, from the same reading. A board that renders "all well" over a mesh
// where nothing can be sent anywhere is worse than a board that is down.
func TestThePageSaysWhichMachinesCannotBeWorkedOut(t *testing.T) {
	open := aMesh(t)
	ctx := t.Context()
	one, two := rivals()
	register(t, open, one)
	register(t, open, two)
	for _, m := range []string{"rival-one", "rival-two"} {
		if _, err := assign(ctx, open, "anchor", m); err != nil && m == "rival-one" {
			t.Fatal(err)
		}
	}
	asked, err := theThreeQuestions(ctx, open)
	if err != nil {
		t.Fatal(err)
	}
	rendered := render(t, viewOf(asked))
	for _, want := range []string{"Can everything be worked out?", "anchor", "the-seat"} {
		if !strings.Contains(rendered, want) {
			t.Fatalf("the page does not say %q:\n%s", want, rendered)
		}
	}
}