cmd/dist: add buildtag parsing test

Forgot to 'git add' this test written as part of CL 359314.

For #41184.

Change-Id: I2ebd48fd62a2053c8b16e5a8c48c1e11d1b86d5b
Reviewed-on: https://go-review.googlesource.com/c/go/+/366894
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/src/cmd/dist/buildtag_test.go b/src/cmd/dist/buildtag_test.go
new file mode 100644
index 0000000000..f64abfd1f1
--- /dev/null
+++ b/src/cmd/dist/buildtag_test.go
@@ -0,0 +1,43 @@
+// Copyright 2021 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 main
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+var buildParserTests = []struct {
+	x       string
+	matched bool
+	err     error
+}{
+	{"gc", true, nil},
+	{"gccgo", false, nil},
+	{"!gc", false, nil},
+	{"gc && gccgo", false, nil},
+	{"gc || gccgo", true, nil},
+	{"gc || (gccgo && !gccgo)", true, nil},
+	{"gc && (gccgo || !gccgo)", true, nil},
+	{"!(gc && (gccgo || !gccgo))", false, nil},
+	{"gccgo || gc", true, nil},
+	{"!(!(!(gccgo || gc)))", false, nil},
+	{"compiler_bootstrap", false, nil},
+	{"cmd_go_bootstrap", true, nil},
+	{"syntax(error", false, fmt.Errorf("parsing //go:build line: unexpected (")},
+	{"(gc", false, fmt.Errorf("parsing //go:build line: missing )")},
+	{"gc gc", false, fmt.Errorf("parsing //go:build line: unexpected tag")},
+	{"(gc))", false, fmt.Errorf("parsing //go:build line: unexpected )")},
+}
+
+func TestBuildParser(t *testing.T) {
+	for _, tt := range buildParserTests {
+		matched, err := matchexpr(tt.x)
+		if matched != tt.matched || !reflect.DeepEqual(err, tt.err) {
+			t.Errorf("matchexpr(%q) = %v, %v; want %v, %v", tt.x, matched, err, tt.matched, tt.err)
+		}
+	}
+}