feat(web): add mw.RequestIDFrom (resolver sees the request); dependency refresh; v1.4.0

mw/requestid_test.go

@@ -0,0 +1,96 @@
+package mw
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"code.nochebuena.dev/einherjar/core/logz"
+)
+
+// A resolver that continues the client's X-Request-ID lands in both the context
+// and the response header.
+func TestRequestIDFrom_HonoursInbound(t *testing.T) {
+	const inbound = "client-supplied-123"
+
+	var ctxID string
+	h := RequestIDFrom(func(r *http.Request) string {
+		return r.Header.Get("X-Request-ID")
+	})(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+		ctxID = logz.GetRequestID(r.Context())
+	}))
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set("X-Request-ID", inbound)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+
+	if ctxID != inbound {
+		t.Errorf("context request id = %q, want %q", ctxID, inbound)
+	}
+	if got := rec.Header().Get("X-Request-ID"); got != inbound {
+		t.Errorf("response header = %q, want %q", got, inbound)
+	}
+}
+
+// Deliberate regression: RequestID(gen) always generates and never honours an
+// inbound X-Request-ID. Callers that want to continue a client id use RequestIDFrom.
+func TestRequestID_AlwaysGenerates_IgnoresInbound(t *testing.T) {
+	const inbound = "client-supplied-123"
+	const generated = "generated-999"
+
+	var ctxID string
+	h := RequestID(func() string { return generated })(
+		http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+			ctxID = logz.GetRequestID(r.Context())
+		}))
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set("X-Request-ID", inbound)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+
+	if ctxID != generated {
+		t.Errorf("context request id = %q, want generated %q (inbound must be ignored)", ctxID, generated)
+	}
+	if got := rec.Header().Get("X-Request-ID"); got != generated {
+		t.Errorf("response header = %q, want %q", got, generated)
+	}
+}
+
+// The resolver runs exactly once per request.
+func TestRequestIDFrom_ResolverCalledOnce(t *testing.T) {
+	calls := 0
+	h := RequestIDFrom(func(*http.Request) string {
+		calls++
+		return "id"
+	})(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))
+
+	h.ServeHTTP(httptest.NewRecorder(), httptest.NewRequest(http.MethodGet, "/", nil))
+
+	if calls != 1 {
+		t.Errorf("resolver called %d times, want 1", calls)
+	}
+}
+
+// An empty resolver result attaches nothing: no context id and no response header,
+// rather than a silently-empty value.
+func TestRequestIDFrom_EmptyResult_AttachesNothing(t *testing.T) {
+	var ctxID string
+	h := RequestIDFrom(func(*http.Request) string { return "" })(
+		http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+			ctxID = logz.GetRequestID(r.Context())
+		}))
+
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.Header.Set("X-Request-ID", "should-be-ignored")
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+
+	if ctxID != "" {
+		t.Errorf("context request id = %q, want empty (nothing attached)", ctxID)
+	}
+	if vals := rec.Header().Values("X-Request-ID"); len(vals) != 0 {
+		t.Errorf("X-Request-ID header = %v on empty resolve; want absent", vals)
+	}
+}