1 files changed, 69 insertions, 0 deletions
diff --git a/starlarkstruct/struct_test.go b/starlarkstruct/struct_test.go
new file mode 100644
index 0000000..4f103bd
--- /dev/null
+++ b/starlarkstruct/struct_test.go
@@ -0,0 +1,69 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package starlarkstruct_test
+
+import (
+	"fmt"
+	"path/filepath"
+	"testing"
+
+	"go.starlark.net/starlark"
+	"go.starlark.net/starlarkstruct"
+	"go.starlark.net/starlarktest"
+)
+
+func Test(t *testing.T) {
+	testdata := starlarktest.DataFile("starlarkstruct", ".")
+	thread := &starlark.Thread{Load: load}
+	starlarktest.SetReporter(thread, t)
+	filename := filepath.Join(testdata, "testdata/struct.star")
+	predeclared := starlark.StringDict{
+		"struct": starlark.NewBuiltin("struct", starlarkstruct.Make),
+		"gensym": starlark.NewBuiltin("gensym", gensym),
+	}
+	if _, err := starlark.ExecFile(thread, filename, nil, predeclared); err != nil {
+		if err, ok := err.(*starlark.EvalError); ok {
+			t.Fatal(err.Backtrace())
+		}
+		t.Fatal(err)
+	}
+}
+
+// load implements the 'load' operation as used in the evaluator tests.
+func load(thread *starlark.Thread, module string) (starlark.StringDict, error) {
+	if module == "assert.star" {
+		return starlarktest.LoadAssertModule()
+	}
+	return nil, fmt.Errorf("load not implemented")
+}
+
+// gensym is a built-in function that generates a unique symbol.
+func gensym(thread *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	var name string
+	if err := starlark.UnpackArgs("gensym", args, kwargs, "name", &name); err != nil {
+		return nil, err
+	}
+	return &symbol{name: name}, nil
+}
+
+// A symbol is a distinct value that acts as a constructor of "branded"
+// struct instances, like a class symbol in Python or a "provider" in Bazel.
+type symbol struct{ name string }
+
+var _ starlark.Callable = (*symbol)(nil)
+
+func (sym *symbol) Name() string          { return sym.name }
+func (sym *symbol) String() string        { return sym.name }
+func (sym *symbol) Type() string          { return "symbol" }
+func (sym *symbol) Freeze()               {} // immutable
+func (sym *symbol) Truth() starlark.Bool  { return starlark.True }
+func (sym *symbol) Hash() (uint32, error) { return 0, fmt.Errorf("unhashable: %s", sym.Type()) }
+
+func (sym *symbol) CallInternal(thread *starlark.Thread, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
+	if len(args) > 0 {
+		return nil, fmt.Errorf("%s: unexpected positional arguments", sym)
+	}
+	return starlarkstruct.FromKeywords(sym, kwargs), nil
+}