Use execa over spawn

package.json

@@ -30,6 +30,7 @@
   },
   "dependencies": {
     "core-js": "^3.46.0",
+    "execa": "^7.2.0",
     "graphql": "^16.11.0"
   },
   "devDependencies": {

src/methods/build-function.ts

@@ -2,10 +2,11 @@
  * Build a function run payload from a cart and options
  */
 
-import { spawn } from "child_process";
 import path from "path";
 import { fileURLToPath } from "url";
 
+import { execa } from "execa";
+
 /**
  * Interface for the build function result
  */
@@ -26,86 +27,56 @@ const __dirname = path.dirname(__filename);
 export async function buildFunction(
   functionPath?: string,
 ): Promise<BuildFunctionResult> {
-  try {
-    let functionDir;
-    let appRootDir;
-    let functionName;
+  let functionDir;
+  let appRootDir;
+  let functionName;
 
-    if (functionPath) {
-      // Use provided function path
-      functionDir = path.resolve(functionPath);
-      appRootDir = path.dirname(functionDir);
-      functionName = path.basename(functionDir);
-    } else {
-      // Calculate paths correctly for when used as a dependency:
-      // __dirname = /path/to/function/tests/node_modules/function-testing-helpers/src/methods
-      // Go up 5 levels to get to function directory: ../../../../../ = /path/to/function
-      functionDir = path.dirname(
-        path.dirname(path.dirname(path.dirname(path.dirname(__dirname)))),
-      );
-      appRootDir = path.dirname(functionDir);
-      functionName = path.basename(functionDir);
-    }
+  if (functionPath) {
+    // Use provided function path
+    functionDir = path.resolve(functionPath);
+    appRootDir = path.dirname(functionDir);
+    functionName = path.basename(functionDir);
+  } else {
+    // Calculate paths correctly for when used as a dependency:
+    // __dirname = /path/to/function/tests/node_modules/function-testing-helpers/src/methods
+    // Go up 5 levels to get to function directory: ../../../../../ = /path/to/function
+    functionDir = path.dirname(
+      path.dirname(path.dirname(path.dirname(path.dirname(__dirname)))),
+    );
+    appRootDir = path.dirname(functionDir);
+    functionName = path.basename(functionDir);
+  }
 
-    return new Promise((resolve, reject) => {
-      const shopifyProcess = spawn(
-        "shopify",
-        ["app", "function", "build", "--path", functionName],
-        {
-          cwd: appRootDir,
-          stdio: ["pipe", "pipe", "pipe"],
-          env: {
-            ...process.env,
-            SHOPIFY_INVOKED_BY: "shopify-function-test-helpers",
-          },
+  try {
+    const result = await execa(
+      "shopify",
+      ["app", "function", "build", "--path", functionName],
+      {
+        cwd: appRootDir,
+        env: {
+          ...process.env,
+          SHOPIFY_INVOKED_BY: "shopify-function-test-helpers",
         },
-      );
+      },
+    );
 
-      let stdout = "";
-      let stderr = "";
-
-      shopifyProcess.stdout.on("data", (data) => {
-        stdout += data.toString();
-      });
-
-      shopifyProcess.stderr.on("data", (data) => {
-        stderr += data.toString();
-      });
-
-      shopifyProcess.on("close", (code) => {
-        if (code !== 0) {
-          reject(
-            new Error(`Build command failed with exit code ${code}: ${stderr}`),
-          );
-          return;
-        }
-
-        resolve({
-          success: true,
-          output: stdout.trim(),
-          error: null,
-        });
-      });
-
-      shopifyProcess.on("error", (error) => {
-        reject(
-          new Error(`Failed to start shopify build command: ${error.message}`),
-        );
-      });
-    });
-  } catch (error) {
-    if (error instanceof Error) {
-      return {
-        success: false,
-        output: null,
-        error: error.message,
-      };
-    } else {
-      return {
-        success: false,
-        output: null,
-        error: "Unknown error occurred during build",
-      };
+    return {
+      success: true,
+      output: result.stdout.trim(),
+      error: null,
+    };
+  } catch (error: any) {
+    // Handle command execution errors (non-zero exit code)
+    if (error?.exitCode !== undefined) {
+      const stderr = error?.stderr || "";
+      throw new Error(
+        `Build command failed with exit code ${error.exitCode}${stderr ? `: ${stderr}` : ""}`,
+      );
     }
+
+    // Handle spawn/process errors (command not found, etc.)
+    throw new Error(
+      `Failed to start shopify build command: ${error?.message || String(error)}`,
+    );
   }
 }