Add test for apply/refresh on locked state files

Verify that these operations fail when a state file is locked.

command/apply_test.go

@@ -8,12 +8,10 @@ import (
 	"net/http"
 	"net/url"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"reflect"
 	"strings"
 	"sync"
-	"syscall"
 	"testing"
 	"time"
 
@@ -65,13 +63,11 @@ func TestApply(t *testing.T) {
 func TestApply_lockedState(t *testing.T) {
 	statePath := testTempFile(t)
 
-	locker := exec.Command("go", "run", "testadata/statelocker.go", statePath)
-	locker.Stderr = os.Stderr
-	if err := locker.Start(); err != nil {
+	unlock, err := testLockState(statePath)
+	if err != nil {
 		t.Fatal(err)
 	}
-
-	defer locker.Process.Signal(syscall.SIGTERM)
+	defer unlock()
 
 	p := testProvider()
 	ui := new(cli.MockUi)
@@ -86,8 +82,13 @@ func TestApply_lockedState(t *testing.T) {
 		"-state", statePath,
 		testFixturePath("apply"),
 	}
-	if code := c.Run(args); code != 0 {
-		t.Fatalf("bad: %d\n\n%s", code, ui.ErrorWriter.String())
+	if code := c.Run(args); code == 0 {
+		t.Fatal("expected error")
+	}
+
+	output := ui.ErrorWriter.String()
+	if !strings.Contains(output, "locked") {
+		t.Fatal("command output does not look like a lock error:", output)
 	}
 }
 

command/command_test.go

@@ -6,14 +6,17 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"flag"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
+	"syscall"
 	"testing"
 
 	"github.com/hashicorp/go-getter"
@@ -529,3 +532,37 @@ func testRemoteState(t *testing.T, s *terraform.State, c int) (*terraform.Remote
 
 	return remote, srv
 }
+
+// testlockState calls a separate process to the lock the state file at path.
+// deferFunc should be called in the caller to properly unlock the file.
+func testLockState(path string) (func(), error) {
+	locker := exec.Command("go", "run", "testdata/statelocker.go", path)
+	pr, pw, err := os.Pipe()
+	if err != nil {
+		return nil, err
+	}
+	defer pr.Close()
+	defer pw.Close()
+	locker.Stderr = pw
+	locker.Stdout = pw
+
+	if err := locker.Start(); err != nil {
+		return nil, err
+	}
+	deferFunc := func() {
+		locker.Process.Signal(syscall.SIGTERM)
+		locker.Wait()
+	}
+
+	// wait for the process to lock
+	buf := make([]byte, 1024)
+	n, err := pr.Read(buf)
+	if err != nil {
+		return deferFunc, fmt.Errorf("read from statelocker returned: %s", err)
+	}
+
+	if string(buf[:n]) != "LOCKED" {
+		return deferFunc, fmt.Errorf("statelocker wrote", string(buf[:n]))
+	}
+	return deferFunc, nil
+}

command/refresh_test.go

@@ -59,6 +59,43 @@ func TestRefresh(t *testing.T) {
 	}
 }
 
+func TestRefresh_lockedState(t *testing.T) {
+	state := testState()
+	statePath := testStateFile(t, state)
+
+	unlock, err := testLockState(statePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer unlock()
+
+	p := testProvider()
+	ui := new(cli.MockUi)
+	c := &RefreshCommand{
+		Meta: Meta{
+			ContextOpts: testCtxConfig(p),
+			Ui:          ui,
+		},
+	}
+
+	p.RefreshFn = nil
+	p.RefreshReturn = &terraform.InstanceState{ID: "yes"}
+
+	args := []string{
+		"-state", statePath,
+		testFixturePath("refresh"),
+	}
+
+	if code := c.Run(args); code == 0 {
+		t.Fatal("expected error")
+	}
+
+	output := ui.ErrorWriter.String()
+	if !strings.Contains(output, "locked") {
+		t.Fatal("command output does not look like a lock error:", output)
+	}
+}
+
 func TestRefresh_badState(t *testing.T) {
 	p := testProvider()
 	ui := new(cli.MockUi)