| 1 | package agent |
| 2 | |
| 3 | import ( |
| 4 | "go/ast" |
| 5 | "go/parser" |
| 6 | "go/token" |
| 7 | "os" |
| 8 | "path/filepath" |
| 9 | "strings" |
| 10 | "testing" |
| 11 | ) |
| 12 | |
| 13 | // configFieldNames is agentConfig's surface, read from the type itself so the |
| 14 | // guard below cannot drift from what the struct actually holds. |
| 15 | func configFieldNames(t *testing.T) map[string]bool { |
| 16 | t.Helper() |
| 17 | fset := token.NewFileSet() |
| 18 | file, err := parser.ParseFile(fset, "agent_config.go", nil, 0) |
| 19 | if err != nil { |
| 20 | t.Fatalf("parse agent_config.go: %v", err) |
| 21 | } |
| 22 | names := map[string]bool{} |
| 23 | ast.Inspect(file, func(n ast.Node) bool { |
| 24 | spec, ok := n.(*ast.TypeSpec) |
| 25 | if !ok || spec.Name.Name != "agentConfig" { |
| 26 | return true |
| 27 | } |
| 28 | st, ok := spec.Type.(*ast.StructType) |
| 29 | if !ok { |
| 30 | return false |
| 31 | } |
| 32 | for _, field := range st.Fields.List { |
| 33 | for _, name := range field.Names { |
| 34 | names[name.Name] = true |
| 35 | } |
| 36 | } |
| 37 | return false |
| 38 | }) |
| 39 | if len(names) == 0 { |
| 40 | t.Fatal("agentConfig has no fields; the guard would pass vacuously") |
| 41 | } |
| 42 | return names |
| 43 | } |
| 44 | |
| 45 | // Field promotion makes `a.contextWindow = x` compile from anywhere in the |
| 46 | // package, so "configuration" is a claim rather than a guarantee. That claim is |
| 47 | // what lets the struct-state ratchet exclude these fields; unenforced, the |
| 48 | // exclusion would just be a way to hide state. So it is checked, not asserted. |
| 49 | func TestAgentConfigIsNeverAssignedAfterConstruction(t *testing.T) { |
| 50 | fields := configFieldNames(t) |
| 51 | entries, err := os.ReadDir(".") |
| 52 | if err != nil { |
| 53 | t.Fatalf("read package dir: %v", err) |
| 54 | } |
| 55 | fset := token.NewFileSet() |
| 56 | for _, entry := range entries { |
| 57 | name := entry.Name() |
| 58 | if !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") { |
| 59 | continue |
| 60 | } |
| 61 | file, err := parser.ParseFile(fset, filepath.Join(".", name), nil, 0) |
| 62 | if err != nil { |
| 63 | t.Fatalf("parse %s: %v", name, err) |
| 64 | } |
| 65 | ast.Inspect(file, func(n ast.Node) bool { |
| 66 | assign, ok := n.(*ast.AssignStmt) |
| 67 | if !ok { |
| 68 | return true |
| 69 | } |
| 70 | for _, lhs := range assign.Lhs { |
| 71 | sel, ok := lhs.(*ast.SelectorExpr) |
| 72 | if !ok || !fields[sel.Sel.Name] { |
| 73 | continue |
| 74 | } |
| 75 | // Only Agent's own receiver: other types (TaskTool) legitimately |
| 76 | // carry same-named fields of their own. |
| 77 | recv, ok := sel.X.(*ast.Ident) |
| 78 | if !ok || recv.Name != "a" { |
| 79 | continue |
| 80 | } |
| 81 | t.Errorf("%s:%d: %s.%s is assigned after construction; agentConfig must stay immutable, or the field belongs on Agent", |
| 82 | name, fset.Position(sel.Pos()).Line, recv.Name, sel.Sel.Name) |
| 83 | } |
| 84 | return true |
| 85 | }) |
| 86 | } |
| 87 | } |
| 88 |