Optimize tsconfig.json file finding

Author: Toke Voltelen

src/lib/utils/options/readers/tsconfig.ts

@@ -37,24 +37,33 @@ export class TSConfigReader extends OptionsComponent {
     onDiscover(event: DiscoverEvent) {
         // Do nothing until were fetching options
         if (event.mode !== OptionsReadMode.Fetch) {
-            return;
+          return;
         }
 
+        let file: string;
+
         if (TSConfigReader.OPTIONS_KEY in event.data) {
-            this.load(event, Path.resolve(event.data[TSConfigReader.OPTIONS_KEY]));
+          const tsconfig = event.data[TSConfigReader.OPTIONS_KEY];
+
+          file = /tsconfig\.json$/.test(tsconfig)
+            ? Path.resolve(tsconfig)
+            : ts.findConfigFile(tsconfig, ts.sys.fileExists);
+
+          if (!file || !FS.existsSync(file)) {
+              event.addError('The tsconfig file %s does not exist.', file);
+              return;
+          }
         } else if (TSConfigReader.PROJECT_KEY in event.data) {
-            // The `project` option may be a directory or file, so use TS to find it
-            let file: string = ts.findConfigFile(event.data[TSConfigReader.PROJECT_KEY], ts.sys.fileExists);
-            // If file is undefined, we found no file to load.
-            if (file) {
-                this.load(event, file);
-            }
+          // The `project` option may be a directory or file, so use TS to find it
+          file = ts.findConfigFile(event.data[TSConfigReader.PROJECT_KEY], ts.sys.fileExists);
         } else if (this.application.isCLI) {
-            let file: string = ts.findConfigFile('.', ts.sys.fileExists);
-            // If file is undefined, we found no file to load.
-            if (file) {
-                this.load(event, file);
-            }
+          // No file or directory has been specified so find the file in the root of the project
+          file = ts.findConfigFile('.', ts.sys.fileExists);
+        }
+
+        // If file is undefined, we found no file to load.
+        if (file) {
+          this.load(event, file);
         }
     }
 
@@ -65,11 +74,6 @@ export class TSConfigReader extends OptionsComponent {
      * @param fileName  The absolute path and file name of the tsconfig file.
      */
     load(event: DiscoverEvent, fileName: string) {
-        if (!FS.existsSync(fileName)) {
-            event.addError('The tsconfig file %s does not exist.', fileName);
-            return;
-        }
-
         const { config } = ts.readConfigFile(fileName, ts.sys.readFile);
         if (config === undefined) {
             event.addError('The tsconfig file %s does not contain valid JSON.', fileName);