test_all: allow an env parameter to set environment variables

fstest/test_all/config.go

@@ -39,6 +39,7 @@ type Backend struct {
 	IgnoreTests []string // paths of tests not to run, blank for none
 	ListRetries int      // -list-retries if > 0
 	ExtraTime   float64  // factor to multiply the timeout by
+	Env         []string // environment variables to set in form KEY=VALUE
 }
 
 // includeTest returns true if this backend should be included in this
@@ -94,6 +95,7 @@ func (b *Backend) MakeRuns(t *Test) (runs []*Run) {
 			Ignore:      ignore,
 			ListRetries: b.ListRetries,
 			ExtraTime:   b.ExtraTime,
+			Env:         b.Env,
 		}
 		if t.AddBackend {
 			run.Path = path.Join(run.Path, b.Backend)

fstest/test_all/run.go

@@ -45,8 +45,9 @@ type Run struct {
 	NoBinary    bool   // set to not build a binary
 	SizeLimit   int64  // maximum test file size
 	Ignore      map[string]struct{}
-	ListRetries int     // -list-retries if > 0
-	ExtraTime   float64 // multiply the timeout by this
+	ListRetries int      // -list-retries if > 0
+	ExtraTime   float64  // multiply the timeout by this
+	Env         []string // environment variables in form KEY=VALUE
 	// Internals
 	CmdLine     []string
 	CmdString   string
@@ -252,6 +253,7 @@ func (r *Run) trial() {
 	cmd.Stderr = multiOut
 	cmd.Stdout = multiOut
 	cmd.Dir = r.Path
+	cmd.Env = append(os.Environ(), r.Env...)
 	start := time.Now()
 	r.err = cmd.Run()
 	r.output = b.Bytes()