chore: refactor nprintf (#654)

Extracted from #622

Also ran goimports for clean up (triggered by stray imports based test
failure)

Author: displague

equinix/provider_test.go

@@ -288,6 +288,11 @@ func (t *testAccConfig) build() string {
 	return t.config
 }
 
+// nprintf returns a string with all the placeholders replaced by the values from the params map
+//
+// Deprecated: nprintf is shared between NE resource tests and has been
+// centralized ahead of those NE resources moving to separate packages.
+// Use github.com/equinix/terraform-provider-equinix/internal/nprintf.NPrintf instead
 func nprintf(format string, params map[string]interface{}) string {
 	for key, val := range params {
 		var strVal string

internal/nprintf/nprintf.go

@@ -0,0 +1,23 @@
+package nprintf
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// NPrintf is a helper function to replace placeholders in a string with values from a map
+func NPrintf(format string, params map[string]interface{}) string {
+	for key, val := range params {
+		var strVal string
+		switch val.(type) {
+		case []string:
+			r := regexp.MustCompile(`" "`)
+			strVal = r.ReplaceAllString(fmt.Sprintf("%q", val), `", "`)
+		default:
+			strVal = fmt.Sprintf("%v", val)
+		}
+		format = strings.Replace(format, "%{"+key+"}", strVal, -1)
+	}
+	return format
+}