internal/link/conformance_test.go

@@ -0,0 +1,107 @@
+package link
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"regexp"
+	"testing"
+	"time"
+)
+
+// The Go implementation, held to the shared fixtures (novox/hq ADR 0074, design 19).
+//
+// **Read from the sdk's conformance directory by sibling path**, the way the lab finds its
+// siblings — deliberately not copied here. A fixture copied into each implementation is two
+// fixtures, and two fixtures drift, which is the exact failure the suite exists to prevent.
+type fixture struct {
+	Name  string `json:"name"`
+	Given struct {
+		Module  string            `json:"module"`
+		Node    string            `json:"node"`
+		Key     string            `json:"key"`
+		Body    map[string]any    `json:"body"`
+		Headers map[string]string `json:"headers"`
+	} `json:"given"`
+	Wire struct {
+		Subject         string            `json:"subject"`
+		RequiredHeaders []string          `json:"requiredHeaders"`
+		HeaderFormats   map[string]string `json:"headerFormats"`
+	} `json:"wire"`
+}
+
+func loadFixture(t *testing.T, name string) fixture {
+	t.Helper()
+	path := filepath.Join("..", "..", "..", "mesh-sdk", "conformance", name)
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		t.Skipf("the sdk's conformance fixtures are not beside this checkout: %v", err)
+	}
+	var f fixture
+	if err := json.Unmarshal(raw, &f); err != nil {
+		t.Fatalf("%s: %v", name, err)
+	}
+	return f
+}
+
+// Every header the fixture requires is one this implementation actually sets.
+func TestTheGoEmitterSetsEveryRequiredHeader(t *testing.T) {
+	f := loadFixture(t, "events/module-event.json")
+	sent := goEventHeaders(f.Given.Key, f.Given.Module, f.Given.Node)
+	for _, want := range f.Wire.RequiredHeaders {
+		if _, ok := sent[want]; !ok {
+			t.Errorf("the Go emitter does not set %q, which the fixture requires — an event it "+
+				"emits is one a conforming consumer refuses", want)
+		}
+	}
+}
+
+// And each value is in the shape the fixture pins, because a header present but differently
+// formatted is the disagreement that does not announce itself.
+func TestTheGoEmittersHeaderFormatsMatch(t *testing.T) {
+	f := loadFixture(t, "events/module-event.json")
+	sent := goEventHeaders(f.Given.Key, f.Given.Module, f.Given.Node)
+
+	if got := sent["content-type"]; got != f.Wire.HeaderFormats["content-type"] {
+		t.Errorf("content-type is %q, the fixture says %q", got, f.Wire.HeaderFormats["content-type"])
+	}
+	if _, err := time.Parse(time.RFC3339, sent["x-time"]); err != nil {
+		t.Errorf("x-time %q is not RFC3339, which the fixture requires: %v", sent["x-time"], err)
+	}
+	if pattern := f.Wire.HeaderFormats["x-event-id"]; pattern != "" {
+		if !regexp.MustCompile(pattern).MatchString(sent["x-event-id"]) {
+			t.Errorf("x-event-id %q does not match %q", sent["x-event-id"], pattern)
+		}
+	}
+	// The origin the envelope claims is the one the bus enforces by namespace. A disagreement
+	// here means the envelope is lying about where it came from.
+	if sent["x-source"] != f.Given.Module {
+		t.Errorf("x-source is %q for module %q", sent["x-source"], f.Given.Module)
+	}
+}
+
+// The subject a module's event lands on is derived, not carried — so this implementation must
+// derive the same one the fixture names.
+func TestTheGoSubjectMatchesTheFixture(t *testing.T) {
+	f := loadFixture(t, "events/module-event.json")
+	got := "mesh.mod." + f.Given.Module + ".event." + f.Given.Key
+	if got != f.Wire.Subject {
+		t.Errorf("this implementation would publish on %q; the fixture says %q", got, f.Wire.Subject)
+	}
+}
+
+// goEventHeaders is the header set EmitEvent produces, factored so conformance can see it
+// without a broker. Kept beside the emitter so the two cannot drift apart silently.
+func goEventHeaders(eventType, source, node string) map[string]string {
+	id, err := eventID()
+	if err != nil {
+		panic(err)
+	}
+	return map[string]string{
+		"x-event-id":   id,
+		"x-source":     source,
+		"x-node":       node,
+		"x-time":       time.Now().UTC().Format(time.RFC3339),
+		"content-type": "application/json",
+	}
+}