up: support check env before start php serve listen

Author: inhere

src/Util/PhpDevServe.php

@@ -11,6 +11,8 @@
 use function explode;
 use function file_exists;
 use function file_get_contents;
+use function is_dir;
+use function is_file;
 use function random_int;
 use function strpos;
 
@@ -173,28 +175,51 @@ public function config(Closure $fn): self
      * @throws Exception
      */
     public function listen(): void
+    {
+        if ($fn = $this->beforeStart) {
+            $fn($this);
+        } else {
+            $this->printDefaultMessage();
+        }
+
+        $command = $this->getCommand();
+
+        Cli::write("<cyan>></cyan> <darkGray>$command</darkGray>");
+        Sys::execute($command);
+    }
+
+    /**
+     * build full command line string
+     *
+     * @param bool $checkEnv
+     *
+     * @return string
+     * @throws Exception
+     */
+    public function getCommand(bool $checkEnv = true): string
     {
         $phpBin  = $this->getPhpBin();
         $svrAddr = $this->getServerAddr();
         // command eg: "php -S 127.0.0.1:8080 -t web web/index.php";
         $command = "$phpBin -S {$svrAddr}";
 
-        if ($this->docRoot) {
-            $command .= " -t {$this->docRoot}";
+        if ($docRoot = $this->docRoot) {
+            if ($checkEnv && !is_dir($docRoot)) {
+                throw new RuntimeException("the document root is not exists. path: $docRoot");
+            }
+
+            $command .= " -t {$docRoot}";
         }
 
         if ($entryFile = $this->getEntryFile()) {
-            $command .= " $entryFile";
-        }
+            if ($checkEnv && !is_file($entryFile)) {
+                throw new RuntimeException("the entry file is not exists. path: $entryFile");
+            }
 
-        if ($fn = $this->beforeStart) {
-            $fn($this);
-        } else {
-            $this->printDefaultMessage();
+            $command .= " $entryFile";
         }
 
-        Cli::write("<cyan>></cyan> <darkGray>$command</darkGray>");
-        Sys::execute($command);
+        return $command;
     }
 
     /**