feature: Exit with proper codes on error

Author: rtfpessoa

README.md

@@ -23,6 +23,7 @@ Diff to Html generates pretty HTML diffs from unified and git diff output in you
 - [Distributions](#distributions)
 - [Setup](#setup)
 - [Usage](#usage)
+- [Exit Status Codes](#exit-status-codes)
   - [Custom HTML wrapper template](#custom-html-wrapper-template)
   - [Examples](#examples)
 - [Contribute](#contribute)
@@ -89,6 +90,14 @@ Usage: diff2html [ flags and/or options ] -- [git diff passthrough flags and opt
 | -v    | --version                | Show version number                                                        |                              |           |
 | -h    | --help                   | Show help                                                                  |                              |           |
 
+
+## Exit Status Codes
+
+* :tada: 0: Success
+* :dizzy_face: 1: Generic Error
+* :cold_sweat: 3: Input diff is empty
+* :cop: 4: Value of `--hwt | --htmlWrapperTemplate` is not a valid file
+
 ### Custom HTML wrapper template
 
 The template is a very based on a simple replace of several placeholders as coded

src/cli.ts

@@ -80,19 +80,21 @@ export async function getInput(inputType: InputType, inputArgs: string[], ignore
 
 export function getOutput(options: Diff2HtmlConfig, config: Configuration, input: string): string {
   if (config.htmlWrapperTemplate && !fs.existsSync(config.htmlWrapperTemplate)) {
+    process.exitCode = 4;
     throw new Error(`Template ('${config.htmlWrapperTemplate}') not found!`);
   }
 
   const diffJson = parse(input, options);
 
-  if (config.formatType === 'html') {
-    const htmlContent = html(diffJson, { ...options });
-    return prepareHTML(htmlContent, config);
-  } else if (config.formatType === 'json') {
-    return JSON.stringify(diffJson);
+  switch (config.formatType) {
+    case 'html': {
+      const htmlContent = html(diffJson, { ...options });
+      return prepareHTML(htmlContent, config);
+    }
+    case 'json': {
+      return JSON.stringify(diffJson);
+    }
   }
-
-  throw new Error(`Wrong output format '${config.formatType}'!`);
 }
 
 export function preview(content: string, format: string): void {

src/main.ts

@@ -12,6 +12,7 @@ export async function main(): Promise<void> {
     const input = await cli.getInput(configuration.inputSource, argv.extraArguments, configuration.ignore);
 
     if (!input) {
+      process.exitCode = 3;
       log.error('The input is empty. Try again.');
       yargs.help();
       return;
@@ -32,6 +33,9 @@ export async function main(): Promise<void> {
       log.print(output);
     }
   } catch (error) {
+    if (process.exitCode === undefined || process.exitCode === 0) {
+      process.exitCode = 1;
+    }
     log.error(error);
   }
 }