test(01-02): add failing test for typed events and context

- Cover Fire/Collect/UntilHandled, priority, panics and bus isolation
- Require towel actor/org/collection/locale accessors on context
- Assert hello command demonstrates all three dispatch modes

towel/context_test.go

@@ -0,0 +1,75 @@
+package towel
+
+import (
+	"context"
+	"go/parser"
+	"go/token"
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestContextAccessorsRoundTrip(t *testing.T) {
+	ctx := context.Background()
+	ctx = WithActor(ctx, "user-1")
+	ctx = WithOrganization(ctx, "org-9")
+	ctx = WithCollection(ctx, "col-3")
+	ctx = WithLocale(ctx, "pl")
+
+	if got, ok := Actor(ctx); !ok || got != "user-1" {
+		t.Fatalf("Actor = (%q, %v)", got, ok)
+	}
+	if got, ok := Organization(ctx); !ok || got != "org-9" {
+		t.Fatalf("Organization = (%q, %v)", got, ok)
+	}
+	if got, ok := Collection(ctx); !ok || got != "col-3" {
+		t.Fatalf("Collection = (%q, %v)", got, ok)
+	}
+	if got, ok := Locale(ctx); !ok || got != "pl" {
+		t.Fatalf("Locale = (%q, %v)", got, ok)
+	}
+
+	other := context.Background()
+	if _, ok := Actor(other); ok {
+		t.Fatal("Actor leaked across contexts")
+	}
+}
+
+func TestNoPackageGlobalRequestState(t *testing.T) {
+	entries, err := os.ReadDir(".")
+	if err != nil {
+		t.Fatal(err)
+	}
+	fset := token.NewFileSet()
+	for _, entry := range entries {
+		name := entry.Name()
+		if entry.IsDir() || !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
+			continue
+		}
+		file, err := parser.ParseFile(fset, name, nil, parser.SkipObjectResolution)
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, spec := range file.Decls {
+			gen, ok := spec.(interface{ TokString() string })
+			_ = gen
+			_ = ok
+		}
+		src, err := os.ReadFile(name)
+		if err != nil {
+			t.Fatal(err)
+		}
+		// Reject package-level request-state variables. Type keys are ok.
+		for _, line := range strings.Split(string(src), "\n") {
+			trim := strings.TrimSpace(line)
+			if strings.HasPrefix(trim, "var ") && !strings.Contains(trim, "struct{}") && !strings.Contains(trim, "key") {
+				if strings.Contains(strings.ToLower(trim), "actor") ||
+					strings.Contains(strings.ToLower(trim), "locale") ||
+					strings.Contains(strings.ToLower(trim), "organization") ||
+					strings.Contains(strings.ToLower(trim), "collection") {
+					t.Fatalf("package-global request state in %s: %s", name, trim)
+				}
+			}
+		}
+	}
+}