1 files changed, 87 insertions, 0 deletions
diff --git a/src/go/importer/importer_test.go b/src/go/importer/importer_test.go
new file mode 100644
index 0000000..0f5121d
--- /dev/null
+++ b/src/go/importer/importer_test.go
@@ -0,0 +1,87 @@
+// Copyright 2017 The Go 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 importer
+
+import (
+	"go/token"
+	"internal/testenv"
+	"io"
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func TestForCompiler(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	const thePackage = "math/big"
+	out, err := exec.Command(testenv.GoToolPath(t), "list", "-f={{context.Compiler}}:{{.Target}}", thePackage).CombinedOutput()
+	if err != nil {
+		t.Fatalf("go list %s: %v\n%s", thePackage, err, out)
+	}
+	target := strings.TrimSpace(string(out))
+	i := strings.Index(target, ":")
+	compiler, target := target[:i], target[i+1:]
+	if !strings.HasSuffix(target, ".a") {
+		t.Fatalf("unexpected package %s target %q (not *.a)", thePackage, target)
+	}
+
+	if compiler == "gccgo" {
+		t.Skip("golang.org/issue/22500")
+	}
+
+	fset := token.NewFileSet()
+
+	t.Run("LookupDefault", func(t *testing.T) {
+		imp := ForCompiler(fset, compiler, nil)
+		pkg, err := imp.Import(thePackage)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if pkg.Path() != thePackage {
+			t.Fatalf("Path() = %q, want %q", pkg.Path(), thePackage)
+		}
+
+		// Check that the fileset positions are accurate.
+		// https://github.com/golang/go#28995
+		mathBigInt := pkg.Scope().Lookup("Int")
+		posn := fset.Position(mathBigInt.Pos()) // "$GOROOT/src/math/big/int.go:25:1"
+		filename := strings.Replace(posn.Filename, "$GOROOT", runtime.GOROOT(), 1)
+		data, err := os.ReadFile(filename)
+		if err != nil {
+			t.Fatalf("can't read file containing declaration of math/big.Int: %v", err)
+		}
+		lines := strings.Split(string(data), "\n")
+		if posn.Line > len(lines) || !strings.HasPrefix(lines[posn.Line-1], "type Int") {
+			t.Fatalf("Object %v position %s does not contain its declaration",
+				mathBigInt, posn)
+		}
+	})
+
+	t.Run("LookupCustom", func(t *testing.T) {
+		lookup := func(path string) (io.ReadCloser, error) {
+			if path != "math/bigger" {
+				t.Fatalf("lookup called with unexpected path %q", path)
+			}
+			f, err := os.Open(target)
+			if err != nil {
+				t.Fatal(err)
+			}
+			return f, nil
+		}
+		imp := ForCompiler(fset, compiler, lookup)
+		pkg, err := imp.Import("math/bigger")
+		if err != nil {
+			t.Fatal(err)
+		}
+		// Even though we open math/big.a, the import request was for math/bigger
+		// and that should be recorded in pkg.Path(), at least for the gc toolchain.
+		if pkg.Path() != "math/bigger" {
+			t.Fatalf("Path() = %q, want %q", pkg.Path(), "math/bigger")
+		}
+	})
+}