fancy-dns/internal/app/contract_test.go

package app

import (
	"bufio"
	"encoding/json"
	"io"
	"net/http"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"testing"

	"git.k8s-git-k6n.net/mats/fancy-dns/internal/config"
)

// The contract tests in this file exist because the console's TypeScript types
// are hand-written and `apiFetch` ends in `JSON.parse(text) as T`, so nothing
// in the toolchain compared them with the Go structs. A field that lost its
// json tag, or a response a struct never had, showed up as an empty table in a
// browser and nowhere else: the Go suite was green and the console was wrong.
//
// Each assertion is the EXACT top-level key set of one endpoint, driven
// through the real router with the real hook implementations (harness_test.go
// wires a whole App). Renaming a field on either side now fails here with a
// readable diff instead of in a browser.
//
// The sets below are the Go side's truth. Where the console disagrees, the
// console is what has to move: these are the endpoints a deployed binary
// answers, and a contract that follows the UI would drag the API backwards
// every time the UI got nicer. TestConsoleWritePayloadsAreAccepted pins the
// other direction, because there the console is the client and its payload is
// fixed.

// keysOf returns the sorted top-level keys of a JSON object body.
func keysOf(t *testing.T, body []byte) []string {
	t.Helper()
	var m map[string]json.RawMessage
	if err := json.Unmarshal(body, &m); err != nil {
		t.Fatalf("body is not a JSON object: %v\n%s", err, body)
	}
	out := make([]string, 0, len(m))
	for k := range m {
		out = append(out, k)
	}
	sort.Strings(out)
	return out
}

// keysOfField returns the sorted keys of a nested object addressed by path,
// where a numeric path element indexes an array.
func keysOfField(t *testing.T, body []byte, path ...string) []string {
	t.Helper()
	var cur any
	if err := json.Unmarshal(body, &cur); err != nil {
		t.Fatalf("body is not JSON: %v\n%s", err, body)
	}
	for i, p := range path {
		switch node := cur.(type) {
		case map[string]any:
			next, ok := node[p]
			if !ok {
				t.Fatalf("%s: no such key %q at depth %d\n%s", strings.Join(path, "."), p, i, body)
			}
			cur = next
		case []any:
			idx, err := strconv.Atoi(p)
			if err != nil || idx >= len(node) {
				t.Fatalf("%s: %q is not a valid index (len %d)", strings.Join(path, "."), p, len(node))
			}
			cur = node[idx]
		default:
			t.Fatalf("%s: %q is not addressable at depth %d", strings.Join(path, "."), p, i)
		}
	}
	obj, ok := cur.(map[string]any)
	if !ok {
		t.Fatalf("%s: is not an object", strings.Join(path, "."))
	}
	out := make([]string, 0, len(obj))
	for k := range obj {
		out = append(out, k)
	}
	sort.Strings(out)
	return out
}

func wantKeys(want ...string) []string {
	out := append([]string(nil), want...)
	sort.Strings(out)
	return out
}

func requireKeys(t *testing.T, what string, got, want []string) {
	t.Helper()
	if strings.Join(got, ",") == strings.Join(want, ",") {
		return
	}
	t.Errorf("%s JSON keys drifted.\n got: %s\nwant: %s", what,
		strings.Join(got, ", "), strings.Join(want, ", "))
	t.Log("A key the console does not read is harmless but means the Go side grew " +
		"a field nobody agreed on: put it in web/src/lib/types.ts or take it off " +
		"the wire. A key the console reads and this test does not list is a field " +
		"that works today and will break the console the moment the struct changes.")
}

// TestAdminEndpointKeySets is the table: one entry per admin read endpoint the
// console calls, with its exact key set.
func TestAdminEndpointKeySets(t *testing.T) {
	h := newHarness(t, nil)
	// One query, so the log and the cache-top tables have a row to shape.
	// Asserting a key set against an empty list proves only the envelope.
	h.query("hot.test.", 1)
	h.query("hot.test.", 1)

	t.Run("status", func(t *testing.T) {
		code, body := h.get("/api/status")
		if code != http.StatusOK {
			t.Fatalf("GET /api/status = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/status", keysOf(t, body),
			wantKeys("components", "config", "started", "uptime_s", "version"))
	})

	t.Run("blocklists", func(t *testing.T) {
		code, body := h.get("/api/blocklists")
		if code != http.StatusOK {
			t.Fatalf("GET /api/blocklists = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/blocklists", keysOf(t, body),
			wantKeys("digest", "errors", "items", "stats"))
		// items[0] is where drift item 1 bit: blocklist.Source had no json
		// tags at all, so the Sources table rendered blank rows and its
		// per-row toggle posted `name: undefined`.
		requireKeys(t, "GET /api/blocklists items[0]", keysOfField(t, body, "items", "0"),
			wantKeys("digest", "format", "meta", "name", "stats"))
		requireKeys(t, "GET /api/blocklists items[0].meta", keysOfField(t, body, "items", "0", "meta"),
			wantKeys("bytes", "duration", "enabled", "err", "etag", "format",
				"http_status", "last_mod", "name", "path", "rules", "stale",
				"updated_at", "url"))
	})

	// The rules the console's table reads all come from /api/domains, which
	// serves both block and allow rules.
	t.Run("domains", func(t *testing.T) {
		code, body := h.get("/api/domains?per_page=5")
		if code != http.StatusOK {
			t.Fatalf("GET /api/domains = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/domains", keysOf(t, body),
			wantKeys("items", "page", "per_page", "total", "truncated"))
		requireKeys(t, "GET /api/domains items[0]", keysOfField(t, body, "items", "0"),
			wantKeys("action", "categories", "hits", "name", "rule", "source"))
	})

	t.Run("clients", func(t *testing.T) {
		code, body := h.get("/api/clients")
		if code != http.StatusOK {
			t.Fatalf("GET /api/clients = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/clients", keysOf(t, body),
			wantKeys("default_policy", "default_rate_limit", "groups"))
		// Drift item 2: the summary was flat where the console reads `match`,
		// so every group card read "matches nothing" and the editor sent a
		// shape the server refused. `comment` stays omitempty: a group without
		// one must not carry a key the console would have to special-case.
		// `source` is omitted for a group from the config file. It is present
		// here because the queries above made groups[0] the "(default)"
		// traffic bucket, which is reported as source "history".
		requireKeys(t, "GET /api/clients groups[0]", keysOfField(t, body, "groups", "0"),
			wantKeys("allow_domains", "blocked_count", "client_count",
				"deny_domains", "log_queries", "match", "max_concurrent", "matched",
				"name", "policy", "query_count", "rate_limit", "skip_blocklist",
				"skip_cache", "source", "upstreams"))
		requireKeys(t, "GET /api/clients groups[0].match", keysOfField(t, body, "groups", "0", "match"),
			wantKeys("any", "cidrs", "ptr_suffixes", "tags"))
	})

	t.Run("upstreams", func(t *testing.T) {
		code, body := h.get("/api/upstreams")
		if code != http.StatusOK {
			t.Fatalf("GET /api/upstreams = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/upstreams", keysOf(t, body), wantKeys(
			"bootstraps", "breaker_cooldown", "breaker_threshold",
			"healthcheck_interval", "max_attempts", "policy", "servers",
		))
		requireKeys(t, "GET /api/upstreams servers[0]", keysOfField(t, body, "servers", "0"),
			wantKeys("addr", "avg_ms", "breaker_open", "fail_rate", "failures",
				"health", "latency_ms", "p95_ms", "proto", "queries", "server_name",
				"weight"))
	})

	t.Run("cache", func(t *testing.T) {
		code, body := h.get("/api/cache")
		if code != http.StatusOK {
			t.Fatalf("GET /api/cache = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/cache", keysOf(t, body), wantKeys(
			"bytes", "bytes_human", "enabled", "entries", "evictions", "hit_rate",
			"hits", "max_ttl_ms", "min_ttl_ms", "misses", "negative_ttl_ms",
			"persisted", "serve_stale_ms", "shards", "size", "stale_hits",
		))
		requireKeys(t, "GET /api/cache persisted", keysOfField(t, body, "persisted"), wantKeys(
			"bytes", "enabled", "entries", "errors", "last_snapshot", "loaded",
			"path", "writes",
		))
	})

	t.Run("settings", func(t *testing.T) {
		code, body := h.get("/api/settings")
		if code != http.StatusOK {
			t.Fatalf("GET /api/settings = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/settings", keysOf(t, body), wantKeys(
			"config_yaml", "defaults_yaml", "effective_yaml", "last_error",
			"path", "reload_available", "version", "writable",
		))
	})

	t.Run("whoami", func(t *testing.T) {
		code, body := h.get("/api/whoami")
		if code != http.StatusOK {
			t.Fatalf("GET /api/whoami = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/whoami", keysOf(t, body),
			wantKeys("auth_mode", "base_path", "can_write", "mode", "name", "read_only"))
	})
}

// TestWriteEndpointKeySets pins the small write responses.
func TestWriteEndpointKeySets(t *testing.T) {
	h := newHarness(t, nil)

	t.Run("blocklist refresh", func(t *testing.T) {
		code, body := h.do(http.MethodPost, "/api/blocklists/refresh", `{"names":[]}`)
		if code != http.StatusOK {
			t.Fatalf("POST /api/blocklists/refresh = %d: %s", code, body)
		}
		requireKeys(t, "POST /api/blocklists/refresh", keysOf(t, body), wantKeys("names", "started"))
		// The toast used to say "0 sources queued": names is a slice, and a
		// nil slice marshals to null, which the console counted as zero.
		var got struct {
			Names []string `json:"names"`
		}
		if err := json.Unmarshal(body, &got); err != nil {
			t.Fatal(err)
		}
		if got.Names == nil {
			t.Errorf("names is null, so the console's source count is a lie: %s", body)
		}
	})

	t.Run("cache flush", func(t *testing.T) {
		code, body := h.do(http.MethodPost, "/api/cache/flush", "")
		if code != http.StatusOK {
			t.Fatalf("POST /api/cache/flush = %d: %s", code, body)
		}
		requireKeys(t, "POST /api/cache/flush", keysOf(t, body), wantKeys("entries", "ok"))
	})

	t.Run("acl save", func(t *testing.T) {
		code, body := h.do(http.MethodPut, "/api/clients", `{"groups":[],"default_policy":"allow"}`)
		if code != http.StatusOK {
			t.Fatalf("PUT /api/clients = %d: %s", code, body)
		}
		requireKeys(t, "PUT /api/clients", keysOf(t, body), wantKeys("ok", "version"))
	})

	t.Run("upstream save", func(t *testing.T) {
		code, body := h.do(http.MethodPut, "/api/upstreams",
			`{"policy":"parallel","servers":[{"addr":"127.0.0.1:5300","proto":"udp","weight":1}],`+
				`"bootstraps":[],"max_attempts":1,"breaker_threshold":5,"healthcheck_interval":"30s"}`)
		if code != http.StatusOK {
			t.Fatalf("PUT /api/upstreams = %d: %s", code, body)
		}
		requireKeys(t, "PUT /api/upstreams", keysOf(t, body), wantKeys("ok", "version"))
	})
}

// TestConsoleWritePayloadsAreAccepted drives the two write endpoints with the
// exact payload web/src builds. Both answered 400 with `json: unknown field
// ...`, and no hand-written Go test found it: the suite never sent what the
// console actually sends.
func TestConsoleWritePayloadsAreAccepted(t *testing.T) {
	h := newHarness(t, nil)

	t.Run("clients", func(t *testing.T) {
		// web/src/pages/Clients.tsx toGroup(): match is nested, and the
		// console sends the ClientGroup shape without the server-owned
		// counters (client_count, query_count, blocked_count, matched).
		const body = `{"groups":[{
			"name":"console",
			"comment":"from the console",
			"policy":"allow",
			"match":{"cidrs":["10.0.0.0/8"],"ptr_suffixes":["lan.example."],"tags":["laptop"],"any":false},
			"allow_domains":["*.example.net"],
			"deny_domains":["*.ads.example.net"],
			"skip_blocklist":false,
			"skip_cache":false,
			"rate_limit":10,
			"max_concurrent":0,
			"log_queries":true,
			"upstreams":[]
		}],"default_policy":"allow"}`
		code, res := h.do(http.MethodPut, "/api/clients", body)
		if code != http.StatusOK {
			t.Fatalf("PUT /api/clients with the console payload = %d: %s", code, res)
		}
		// And it must round-trip: what the console sent comes back in the
		// shape it sent, or the editor empties itself on refetch.
		_, list := h.get("/api/clients")
		var got struct {
			Groups []struct {
				Name  string `json:"name"`
				Match struct {
					CIDRs []string `json:"cidrs"`
					Tags  []string `json:"tags"`
				} `json:"match"`
			} `json:"groups"`
		}
		if err := json.Unmarshal(list, &got); err != nil {
			t.Fatal(err)
		}
		if len(got.Groups) != 1 {
			t.Fatalf("the saved group did not come back: %s", list)
		}
		if got.Groups[0].Name != "console" {
			t.Errorf("group name = %q, want console", got.Groups[0].Name)
		}
		if len(got.Groups[0].Match.CIDRs) != 1 || got.Groups[0].Match.CIDRs[0] != "10.0.0.0/8" {
			t.Errorf("match.cidrs = %v, want [10.0.0.0/8]; the nested shape must survive", got.Groups[0].Match.CIDRs)
		}
		if len(got.Groups[0].Match.Tags) != 1 {
			t.Errorf("match.tags = %v, want [laptop]", got.Groups[0].Match.Tags)
		}
	})

	t.Run("upstreams", func(t *testing.T) {
		// web/src/pages/Upstreams.tsx save(): the console sends the whole
		// server object it read, including the runtime health fields, with a
		// comment saying the server ignores them. Refusing them is drift
		// item 4 — every save in the console answered 400.
		const body = `{"policy":"failover","max_attempts":2,"breaker_threshold":5,
			"healthcheck_interval_s":30,
			"servers":[{"addr":"127.0.0.1:5300","proto":"udp","server_name":"",
				"insecure_skip_verify":false,"weight":1,"comment":"",
				"health":"down","latency_ms":0,"fail_rate":0,"breaker_open":false,
				"queries":0,"avg_ms":0,"p95_ms":0}],
			"bootstraps":[{"name":"quad9","addresses":["9.9.9.9"],"refresh":"24h"}]}`
		code, res := h.do(http.MethodPut, "/api/upstreams", body)
		if code != http.StatusOK {
			t.Fatalf("PUT /api/upstreams with the console payload = %d: %s", code, res)
		}
		// The duration string form must survive the round trip too, or the
		// console's duration inputs show a nanosecond count.
		_, list := h.get("/api/upstreams")
		var got struct {
			HealthCheck json.RawMessage `json:"healthcheck_interval"`
			Cooldown    json.RawMessage `json:"breaker_cooldown"`
			Servers     []struct {
				Addr string `json:"addr"`
			} `json:"servers"`
			Bootstraps []struct {
				Name    string          `json:"name"`
				Refresh json.RawMessage `json:"refresh"`
			} `json:"bootstraps"`
		}
		if err := json.Unmarshal(list, &got); err != nil {
			t.Fatal(err)
		}
		if string(got.HealthCheck) != `"30s"` {
			t.Errorf("healthcheck_interval = %s, want \"30s\"", got.HealthCheck)
		}
		if string(got.Cooldown) == "" {
			t.Error("breaker_cooldown disappeared from the response")
		}
		if len(got.Servers) != 1 || got.Servers[0].Addr != "127.0.0.1:5300" {
			t.Fatalf("servers = %+v, want the saved 127.0.0.1:5300", got.Servers)
		}
		if len(got.Bootstraps) != 1 || got.Bootstraps[0].Name != "quad9" {
			t.Fatalf("bootstraps = %+v, want the saved quad9", got.Bootstraps)
		}
		// Go's canonical spelling of 24h, which is what Duration.MarshalJSON
		// writes and what the console's duration parser accepts.
		if string(got.Bootstraps[0].Refresh) != `"24h0m0s"` {
			t.Errorf("bootstraps[0].refresh = %s, want a duration string", got.Bootstraps[0].Refresh)
		}
	})
}

// TestRemainingEndpointKeySets covers the endpoints the first pass left out:
// the domain check (which has three distinct shapes, one of them an error
// delivered as 200), the log clear, the settings writes and the first SSE
// frame. A key set the console reads but no test pins is a field that works
// today and breaks the console the first time somebody tidies a struct.
func TestRemainingEndpointKeySets(t *testing.T) {
	h := newHarness(t, nil)

	t.Run("domain check miss", func(t *testing.T) {
		code, body := h.get("/api/domains/check?name=nothing.example.test")
		if code != http.StatusOK {
			t.Fatalf("GET /api/domains/check = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/domains/check (no match)", keysOf(t, body),
			wantKeys("action", "matched", "name", "query", "source"))
	})

	t.Run("domain check match", func(t *testing.T) {
		code, body := h.get("/api/domains/check?name=ads.example.com")
		if code != http.StatusOK {
			t.Fatalf("GET /api/domains/check = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/domains/check (match)", keysOf(t, body), wantKeys(
			"action", "categories", "hits", "match_kind", "matched",
			"matched_pattern", "name", "query", "rule", "source",
		))
	})

	t.Run("settings validate", func(t *testing.T) {
		// A document that is valid: the issue lists are present and empty.
		code, body := h.do(http.MethodPost, "/api/settings/validate",
			`{"config_yaml":"listen: 127.0.0.1:5353\n"}`)
		if code != http.StatusOK {
			t.Fatalf("POST /api/settings/validate = %d: %s", code, body)
		}
		requireKeys(t, "POST /api/settings/validate", keysOf(t, body),
			wantKeys("errors", "ok", "warnings"))
		// A malformed document is still a 200 with a populated `errors`: the
		// console renders the field list, so the envelope is the same.
		code, body = h.do(http.MethodPost, "/api/settings/validate", `{"config_yaml":"\t- :\n"}`)
		if code != http.StatusOK {
			t.Fatalf("POST /api/settings/validate (bad yaml) = %d: %s", code, body)
		}
		requireKeys(t, "POST /api/settings/validate (bad yaml)", keysOf(t, body),
			wantKeys("errors", "ok", "warnings"))
		var bad struct {
			Errors []struct{ Field, Message string } `json:"errors"`
		}
		if err := json.Unmarshal(body, &bad); err != nil {
			t.Fatal(err)
		}
		if len(bad.Errors) == 0 {
			t.Errorf("a malformed document validated clean: %s", body)
		}
	})

	t.Run("settings save and reload", func(t *testing.T) {
		doc := h.OriginalConfig()
		code, body := h.do(http.MethodPut, "/api/settings", `{"config_yaml":`+quote(doc)+`}`)
		if code != http.StatusOK {
			t.Fatalf("PUT /api/settings = %d: %s", code, body)
		}
		requireKeys(t, "PUT /api/settings", keysOf(t, body), wantKeys("ok", "version", "warnings"))
		code, body = h.do(http.MethodPost, "/api/settings/reload", "")
		if code != http.StatusOK {
			t.Fatalf("POST /api/settings/reload = %d: %s", code, body)
		}
		requireKeys(t, "POST /api/settings/reload", keysOf(t, body), wantKeys("ok", "version"))
	})

}

// quote renders a Go string as a JSON string literal.
// TestZoneEndpointKeySets pins the zone list and the records inside it.
//
// The zone list is the one shape on this side of the API that a test cannot
// assert from an empty list: an envelope proves nothing about a record, and a
// record is the thing the console renders row by row. So this builds a zone
// through the write endpoint, delegates a name in it, and pins every level.
func TestZoneEndpointKeySets(t *testing.T) {
	managed := filepath.Join(t.TempDir(), "zones")
	h := newHarness(t, func(c *config.Config) { c.Block.ManagedZones = managed })

	write := func(t *testing.T, method, path, body string) {
		t.Helper()
		code, out := h.do(method, path, body)
		if code != http.StatusOK {
			t.Fatalf("%s %s = %d: %s", method, path, code, out)
		}
	}
	// A zone needs a server list before it can hold anything, and a
	// delegation is the other way to start one.
	write(t, http.MethodPost, "/api/zones/records", `{"zone":"console.test.","name":"console.test.","type":"NS","value":"ns1.console.test."}`)
	write(t, http.MethodPost, "/api/zones/records", `{"zone":"console.test.","name":"www.console.test.","type":"A","ttl":60,"value":"10.9.9.9"}`)
	write(t, http.MethodPost, "/api/zones/delegations", `{"zone":"console.test.","name":"sub.console.test.","targets":["ns1.sub.console.test."]}`)

	t.Run("zones", func(t *testing.T) {
		code, body := h.get("/api/zones")
		if code != http.StatusOK {
			t.Fatalf("GET /api/zones = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/zones", keysOf(t, body),
			wantKeys("built_at", "error", "files", "managed_dir", "records", "types", "writable", "zones"))
	})
	t.Run("zone", func(t *testing.T) {
		code, body := h.get("/api/zones")
		if code != http.StatusOK {
			t.Fatalf("GET /api/zones = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/zones zones[]", keysOfField(t, body, "zones", "0"),
			wantKeys("default_ttl", "delegations", "files", "managed", "origin", "record_count", "records", "serial", "soa"))
	})
	t.Run("record", func(t *testing.T) {
		code, body := h.get("/api/zones")
		if code != http.StatusOK {
			t.Fatalf("GET /api/zones = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/zones zones[].records[]", keysOfField(t, body, "zones", "0", "records", "0"),
			wantKeys("delegation", "managed", "name", "source", "ttl", "type", "value", "wildcard"))
	})
	t.Run("delegation", func(t *testing.T) {
		code, body := h.get("/api/zones")
		if code != http.StatusOK {
			t.Fatalf("GET /api/zones = %d: %s", code, body)
		}
		requireKeys(t, "GET /api/zones zones[].delegations[]", keysOfField(t, body, "zones", "0", "delegations", "0"),
			wantKeys("managed", "name", "targets"))
	})
}

func quote(s string) string {
	b, err := json.Marshal(s)
	if err != nil {
		panic(err)
	}
	return string(b)
}

// lineReader reads \n-terminated lines off the SSE stream, which is what
// bufio.Scanner would be for — except Scanner's default 64 KiB cap turns a long
// data frame into "token too long" and the test would fail on payload size
// rather than on the contract.
type lineReader struct {
	r   *bufio.Reader
	buf []byte
}

func newLineReader(r io.Reader) *lineReader {
	return &lineReader{r: bufio.NewReader(r), buf: make([]byte, 0, 4096)}
}

func (l *lineReader) readLine() (string, error) {
	l.buf = l.buf[:0]
	for {
		chunk, isPrefix, err := l.r.ReadLine()
		if err != nil {
			return "", err
		}
		l.buf = append(l.buf, chunk...)
		if !isPrefix {
			return string(l.buf), nil
		}
	}
}