testscript: make sure work dir isn't removed when -testwork is used (#80)

When passing -testwork to go test, the work directory shouldn't
be removed.

Author: leitzler

testscript/testdata/nothing.txt

@@ -0,0 +1 @@
+# Intentionally blank file, used to test that -testwork doesn't remove the work directory 

testscript/testscript.go

@@ -174,7 +174,7 @@ func RunT(t T, p Params) {
 				deferred:    func() {},
 			}
 			defer func() {
-				if p.TestWork {
+				if p.TestWork || *testWork {
 					return
 				}
 				removeAll(ts.workdir)

testscript/testscript_test.go

@@ -8,9 +8,11 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"os/signal"
 	"path/filepath"
 	"reflect"
+	"regexp"
 	"strconv"
 	"testing"
 	"time"
@@ -121,6 +123,32 @@ func TestScripts(t *testing.T) {
 	// TODO check that the temp directory has been removed.
 }
 
+// TestTestwork tests that using the flag -testwork will make sure the work dir isn't removed
+// after the test is done. It uses an empty testscript file that doesn't do anything.
+func TestTestwork(t *testing.T) {
+	out, err := exec.Command("go", "test", ".", "-testwork", "-v", "-run", "TestScripts/^nothing$").CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	re := regexp.MustCompile(`\s+WORK=(\S+)`)
+	match := re.FindAllStringSubmatch(string(out), -1)
+
+	// Ensure that there is only one line with one match
+	if len(match) != 1 || len(match[0]) != 2 {
+		t.Fatalf("failed to extract WORK directory")
+	}
+
+	var fi os.FileInfo
+	if fi, err = os.Stat(match[0][1]); err != nil {
+		t.Fatalf("failed to stat expected work directory %v: %v", match[0][1], err)
+	}
+
+	if !fi.IsDir() {
+		t.Fatalf("expected persisted workdir is not a directory: %v", match[0][1])
+	}
+}
+
 func setSpecialVal(ts *TestScript, neg bool, args []string) {
 	ts.Setenv("SPECIALVAL", "42")
 }