Add lint to check JSON data file prettification (#4320)

* Add test for check JSON data file prettification

* Move prettification test to out linting script

* Add other newline in error message to improve readability

* Invert the diff to show the solution to the user

* Add 'jest-diff' as direct dependency

* Remove annotations and colors

* Replace CRLF newlines with LFs in JSON prettification lint

* Restore colors in JSON prettification lint

.editorconfig

@@ -19,6 +19,5 @@ insert_final_newline=false
 trim_trailing_whitespace=false # Templates with trailing whitespace are more usable
 
 [_data/simple-icons.json]
-indent_style=space
 indent_size=4
 trim_trailing_whitespace=true

package.json

@@ -20,6 +20,7 @@
   "devDependencies": {
     "editorconfig-checker": "3.3.0",
     "jest": "26.6.3",
+    "jest-diff": "26.6.2",
     "jsonlint2": "1.7.1",
     "npm-run-all": "4.1.5",
     "svg-path-bbox": "0.1.5",

scripts/lint.js

@@ -2,15 +2,22 @@
 /**
  * @fileoverview Lints for the package that can't be implemented in the existing linters (e.g. jsonlint/svglint)
  */
+ 
+const fs = require("fs");
+const path = require("path");
 
-const { icons } = require("../_data/simple-icons.json");
+const { diffLinesUnified } = require("jest-diff");
+
+const simpleIconsData = require("../_data/simple-icons.json");
+const simpleIconsDataFile = path.resolve(
+  __dirname, "..", "_data", "simple-icons.json");
 
 /**
  * Contains our tests so they can be isolated from eachother; I don't think each test is worth its own file
  * @type {{[k:string]: () => (string|undefined)}}
  */
 const TESTS = {
-  /** Tests whether our icons are in alphabetical order */
+  /* Tests whether our icons are in alphabetical order */
   alphabetical: function() {
     const collector = (invalidEntries, icon, index, array) => {
       if (index > 0) {
@@ -22,11 +29,27 @@ const TESTS = {
       return invalidEntries;
     };
 
-    const invalids = icons.reduce(collector, []);
+    const invalids = simpleIconsData.icons.reduce(collector, []);
     if (invalids.length) {
       return `Some icons aren't in alphabetical order:
         ${invalids.map(icon => icon.title).join(", ")}`;
     }
+  },
+
+  /* Check the prettification of the data file */
+  prettified: function() {
+    const simpleIconsDataString = fs.readFileSync(
+      simpleIconsDataFile, "utf8").replace(/\r\n/g, '\n');
+    const simpleIconsDataPretty = `${JSON.stringify(simpleIconsData, null, "    ")}\n`;
+    if (simpleIconsDataString !== simpleIconsDataPretty) {
+      const dataDiff = diffLinesUnified(simpleIconsDataString.split("\n"),
+                                        simpleIconsDataPretty.split("\n"),
+                                        {
+                                          expand: false,
+                                          omitAnnotationLines: true
+                                        });
+      return `Data file is not prettified:\n\n${dataDiff}`;
+    }
   }
 };