Move response file handling to a separate package

sbox is going to need to read and write response files, move ReadRspFile
to its own package.

Test: response_test.go
Change-Id: Iecb5486b4aaeb2531828743ad8ef784df675e18e

response/response_test.go

@@ -0,0 +1,96 @@
+// Copyright 2021 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package response
+
+import (
+	"bytes"
+	"reflect"
+	"testing"
+)
+
+func TestReadRspFile(t *testing.T) {
+	testCases := []struct {
+		name, in string
+		out      []string
+	}{
+		{
+			name: "single quoting test case 1",
+			in:   `./cmd '"'-C`,
+			out:  []string{"./cmd", `"-C`},
+		},
+		{
+			name: "single quoting test case 2",
+			in:   `./cmd '-C`,
+			out:  []string{"./cmd", `-C`},
+		},
+		{
+			name: "single quoting test case 3",
+			in:   `./cmd '\"'-C`,
+			out:  []string{"./cmd", `\"-C`},
+		},
+		{
+			name: "single quoting test case 4",
+			in:   `./cmd '\\'-C`,
+			out:  []string{"./cmd", `\\-C`},
+		},
+		{
+			name: "none quoting test case 1",
+			in:   `./cmd \'-C`,
+			out:  []string{"./cmd", `'-C`},
+		},
+		{
+			name: "none quoting test case 2",
+			in:   `./cmd \\-C`,
+			out:  []string{"./cmd", `\-C`},
+		},
+		{
+			name: "none quoting test case 3",
+			in:   `./cmd \"-C`,
+			out:  []string{"./cmd", `"-C`},
+		},
+		{
+			name: "double quoting test case 1",
+			in:   `./cmd "'"-C`,
+			out:  []string{"./cmd", `'-C`},
+		},
+		{
+			name: "double quoting test case 2",
+			in:   `./cmd "\\"-C`,
+			out:  []string{"./cmd", `\-C`},
+		},
+		{
+			name: "double quoting test case 3",
+			in:   `./cmd "\""-C`,
+			out:  []string{"./cmd", `"-C`},
+		},
+		{
+			name: "ninja rsp file",
+			in:   "'a'\nb\n'@'\n'foo'\\''bar'\n'foo\"bar'",
+			out:  []string{"a", "b", "@", "foo'bar", `foo"bar`},
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			got, err := ReadRspFile(bytes.NewBuffer([]byte(testCase.in)))
+			if err != nil {
+				t.Errorf("unexpected error: %q", err)
+			}
+			if !reflect.DeepEqual(got, testCase.out) {
+				t.Errorf("expected %q got %q", testCase.out, got)
+			}
+		})
+	}
+}