Fixes not a directory error (#2813)

src/configuration.ts

@@ -86,19 +86,19 @@ const BUILT_IN_CONFIG = /^tslint:(.*)$/;
 /**
  * Searches for a TSLint configuration and returns the data from the config.
  * @param configFile A path to a config file, this can be null if the location of a config is not known
- * @param inputFileLocation A path to the current file being linted. This is the starting location
+ * @param inputFilePath A path containing the current file being linted. This is the starting location
  * of the search for a configuration.
  * @returns Load status for a TSLint configuration object
  */
 export function findConfiguration(configFile: string | null, inputFilePath: string): IConfigurationLoadResult {
-    const path = findConfigurationPath(configFile, inputFilePath);
-    const loadResult: IConfigurationLoadResult = { path };
+    const configPath = findConfigurationPath(configFile, inputFilePath);
+    const loadResult: IConfigurationLoadResult = { path: configPath };
 
     try {
-        loadResult.results = loadConfigurationFromPath(path);
+        loadResult.results = loadConfigurationFromPath(configPath);
         return loadResult;
     } catch (error) {
-        throw new FatalError(`Failed to load ${path}: ${(error as Error).message}`, error as Error);
+        throw new FatalError(`Failed to load ${configPath}: ${(error as Error).message}`, error as Error);
     }
 }
 
@@ -120,6 +120,21 @@ export function findConfigurationPath(suppliedConfigFilePath: string | null, inp
             return path.resolve(suppliedConfigFilePath);
         }
     } else {
+        // convert to dir if it's a file or doesn't exist
+        let useDirName = false;
+        try {
+            const stats = fs.statSync(inputFilePath);
+            if (stats.isFile()) {
+                useDirName = true;
+            }
+        } catch (e) {
+            // throws if file doesn't exist
+            useDirName = true;
+        }
+        if (useDirName) {
+            inputFilePath = path.dirname(inputFilePath);
+        }
+
         // search for tslint.json from input file location
         let configFilePath = findup(CONFIG_FILENAME, inputFilePath);
         if (configFilePath !== undefined) {

test/configurationTests.ts

@@ -209,6 +209,12 @@ describe("Configuration", () => {
                 findConfigurationPath(null, "./test/files/config-findup"),
                 path.resolve("./test/files/config-findup/tslint.json"),
             );
+
+            // gulp-tslint uses a path including the filename
+            assert.strictEqual(
+                findConfigurationPath(null, "./test/files/config-findup/somefilename.ts"),
+                path.resolve("./test/files/config-findup/tslint.json"),
+            );
         });
     });