feat: respect .prettierignore (#317)

README.md

@@ -113,6 +113,20 @@ for `tslint@^5.0.0`
   }
   ```
 
+## Ignoring files
+
+- It will respect your .prettierignore file in your project root ( process.cwd() ) but if you would like to use a different file you can provide it in the third argument, for example:
+
+  ```json
+  {
+    "extends": ["tslint-plugin-prettier"],
+    "rules": {
+      "prettier": [true, null, { "ignorePath": "otherDirectory/.prettierignore" }]
+    }
+  }
+
+  ```
+
 ## Development
 
 ```sh

src/prettierRule.ts

@@ -7,10 +7,27 @@ import * as ts from 'typescript';
 
 export class Rule extends tslint.Rules.AbstractRule {
   public apply(sourceFile: ts.SourceFile): tslint.RuleFailure[] {
+    if (this.sourceFileIsIgnored(sourceFile, this.ruleArguments)) {
+      return [];
+    }
     return this.applyWithWalker(
       new Walker(sourceFile, this.ruleName, this.ruleArguments),
     );
   }
+  private getIgnorePath(ruleArguments: any[]) {
+    let ignorePath = '.prettierignore';
+    if (ruleArguments.length === 2 && ruleArguments[1].ignorePath) {
+      ignorePath = ruleArguments[1].ignorePath;
+    }
+    return ignorePath;
+  }
+  private sourceFileIsIgnored(sourceFile: ts.SourceFile, ruleArguments: any[]) {
+    const ignorePath = this.getIgnorePath(ruleArguments);
+    const fileInfo = prettier.getFileInfo.sync(sourceFile!.fileName, {
+      ignorePath,
+    });
+    return fileInfo.ignored;
+  }
 }
 
 class Walker extends tslint.AbstractWalker<any[]> {

tests/prettier/prettier-ignored/.prettierignore

@@ -0,0 +1 @@
+prettierIgnoredSyntaxError.ts

tests/prettier/prettier-ignored/prettierIgnoredSyntaxError.ts.lint

@@ -0,0 +1 @@
+hello world

tests/prettier/prettier-ignored/tslint.json

@@ -0,0 +1,6 @@
+{
+  "rulesDirectory": ["../../../rules"],
+  "rules": {
+    "prettier": [true, null, { "ignorePath": "tests/prettier/prettier-ignored/.prettierignore"}]
+  }
+}