Differentiate JSON errors between missing and invalid JSON

src/estimate.js

@@ -1,5 +1,5 @@
 import fs from "fs";
-import path from "path";
+import { readConfig, readRecipe } from "./utils";
 import ndjson from "ndjson";
 import tarea from "@turf/area";
 import tilebelt from "@mapbox/tilebelt";
@@ -85,19 +85,9 @@ const sizeJob = function (pwd, cnf, recipe) {
 
 export default function estimate() {
   const pwd = process.cwd();
-  let cnf, recipe;
-  try {
-    cnf = JSON.parse(fs.readFileSync(path.join(pwd, "mts-config.json")));
-  } catch (err) {
-    console.log("Missing mts-config.json in this directory.");
-    console.log("Run mtsds --config to generate.");
-  }
-  try {
-    recipe = JSON.parse(fs.readFileSync(path.join(pwd, "mts-recipe.json")));
-  } catch (err) {
-    console.log("Missing mts-recipe.json in this directory.");
-    console.log("Run mtsds --config to generate.");
-  }
+
+  const cnf = readConfig(pwd);
+  const recipe = readRecipe(pwd);
 
   if (cnf && recipe) {
     sizeJob(pwd, cnf, recipe);

src/sync.js

@@ -1,7 +1,5 @@
-// import inquirer from "inquirer";
-import fs from "fs";
-import path from "path";
 import sleep from "await-sleep";
+import { readConfig, readRecipe } from "./utils";
 import {
   initService,
   deleteTilesetSource,
@@ -42,19 +40,9 @@ async function runServices(cnf, recipe) {
 
 export default function sync() {
   const pwd = process.cwd();
-  let cnf, recipe;
-  try {
-    cnf = JSON.parse(fs.readFileSync(path.join(pwd, "mts-config.json")));
-  } catch (err) {
-    console.log("Missing mts-config.json in this directory.");
-    console.log("Run mtsds --config to generate.");
-  }
-  try {
-    recipe = JSON.parse(fs.readFileSync(path.join(pwd, "mts-recipe.json")));
-  } catch (err) {
-    console.log("Missing mts-recipe.json in this directory.");
-    console.log("Run mtsds --config to generate.");
-  }
+
+  const cnf = readConfig(pwd);
+  const recipe = readRecipe(pwd);
 
   if (cnf && recipe) {
     runServices(cnf, recipe);

src/utils.js

@@ -0,0 +1,49 @@
+import fs from "fs";
+import path from "path";
+
+const checkFileExistsSync = function(filepath){
+  let flag = true;
+  try {
+    fs.accessSync(filepath, fs.constants.F_OK);
+  } catch (e){
+    flag = false;
+  }
+  return flag;
+};
+
+const readConfig = function (pwd) {
+  const cnfFile = path.join(pwd, "mts-config.json");
+  if (checkFileExistsSync(cnfFile)) {
+    try {
+      const cnf = JSON.parse(fs.readFileSync(cnfFile));
+      return cnf;
+    } catch (err) {
+      console.log("Invalid mts-config.json: parsing failed.");
+      console.log("Verify that mts-config.json is valid JSON.");
+    }
+  } else {
+    console.log("Missing mts-config.json in this directory.");
+    console.log("Run mtsds --config to generate.");
+  }
+};
+
+const readRecipe = function (pwd) {
+  const recipeFile = path.join(pwd, "mts-recipe.json");
+  if (checkFileExistsSync(recipeFile)) {
+    try {
+      const recipe = JSON.parse(fs.readFileSync(recipeFile));
+      return recipe;
+    } catch (err) {
+      console.log("Invalid mts-recipe.json: parsing failed.");
+      console.log("Verify that mts-recipe.json is valid JSON.");
+    }
+  } else {
+    console.log("Missing mts-recipe.json in this directory.");
+    console.log("Run mtsds --config to generate.");
+  }
+};
+
+export {
+  readConfig,
+  readRecipe
+};