add skip-blank-lines option to no-trailing-whitespace (#3346)

src/rules/noTrailingWhitespaceRule.ts

@@ -24,11 +24,13 @@ import { getTemplateRanges } from "./noConsecutiveBlankLinesRule";
 const OPTION_IGNORE_COMMENTS = "ignore-comments";
 const OPTION_IGNORE_JSDOC = "ignore-jsdoc";
 const OPTION_IGNORE_TEMPLATE_STRINGS = "ignore-template-strings";
+const OPTION_IGNORE_BLANK_LINES = "ignore-blank-lines";
 
 interface Options {
     ignoreTemplates: boolean;
     ignoreComments: boolean;
     ignoreJsDoc: boolean;
+    ignoreBlankLines: boolean;
 }
 
 export class Rule extends Lint.Rules.AbstractRule {
@@ -42,13 +44,14 @@ export class Rule extends Lint.Rules.AbstractRule {
 
             * \`"${OPTION_IGNORE_TEMPLATE_STRINGS}"\`: Allows trailing whitespace in template strings.
             * \`"${OPTION_IGNORE_COMMENTS}"\`: Allows trailing whitespace in comments.
-            * \`"${OPTION_IGNORE_JSDOC}"\`: Allows trailing whitespace only in JSDoc comments.`,
+            * \`"${OPTION_IGNORE_JSDOC}"\`: Allows trailing whitespace only in JSDoc comments.
+            * \`"${OPTION_IGNORE_BLANK_LINES}"\`: Allows trailing whitespace on empty lines.`,
         hasFix: true,
         options: {
             type: "array",
             items: {
                 type: "string",
-                enum: [OPTION_IGNORE_COMMENTS, OPTION_IGNORE_JSDOC, OPTION_IGNORE_TEMPLATE_STRINGS],
+                enum: [OPTION_IGNORE_COMMENTS, OPTION_IGNORE_JSDOC, OPTION_IGNORE_TEMPLATE_STRINGS, OPTION_IGNORE_BLANK_LINES],
             },
         },
         optionExamples: [
@@ -66,6 +69,7 @@ export class Rule extends Lint.Rules.AbstractRule {
     public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
         const ignoreComments = this.ruleArguments.indexOf(OPTION_IGNORE_COMMENTS) !== -1;
         return this.applyWithFunction(sourceFile, walk, {
+            ignoreBlankLines: this.ruleArguments.indexOf(OPTION_IGNORE_BLANK_LINES) !== -1,
             ignoreComments,
             ignoreJsDoc: ignoreComments || this.ruleArguments.indexOf(OPTION_IGNORE_JSDOC) !== -1,
             ignoreTemplates: this.ruleArguments.indexOf(OPTION_IGNORE_TEMPLATE_STRINGS) !== -1,
@@ -78,8 +82,9 @@ function walk(ctx: Lint.WalkContext<Options>) {
     const sourceFile = ctx.sourceFile;
     const text = sourceFile.text;
     for (const line of getLineRanges(sourceFile)) {
+        // \s matches any whitespace character (equal to [\r\n\t\f\v ])
         const match = text.substr(line.pos, line.contentLength).match(/\s+$/);
-        if (match !== null) {
+        if (match !== null && !(ctx.options.ignoreBlankLines && match.index === 0)) {
             possibleFailures.push({
                 end: line.pos + line.contentLength,
                 pos: line.pos + match.index!,

test/rules/no-trailing-whitespace/skip-blank-lines/test.ts.fix

@@ -0,0 +1,34 @@
+class Clazz {
+    public funcxion() {
+        console.log("test")   ;
+    }
+
+
+    private foobar() {
+    }
+}
+const template = `
+I have trailing whitespace
+`;
+// single line comment without trailing whitespace
+// single line comment with trailing whitespace
+ /* single line multiline comment */
+/* whitespace after comment */
+/* first line has trailing whitespace
+   second line is ok
+   last line is not checked         */
+/*
+ */
+
+/**
+ * JSDoc comment with trailing whitespace
+ *
+ */
+
+/***
+ * not a JSDoc comment
+ *
+ */
+
+// following line checks for trailing whitespace before EOF
+

test/rules/no-trailing-whitespace/skip-blank-lines/test.ts.lint

@@ -0,0 +1,46 @@
+class Clazz {
+    public funcxion() {    
+                       ~~~~ [trailing whitespace]
+        console.log("test")   ;    
+                               ~~~~ [trailing whitespace]
+    }
+
+
+    private foobar() {
+    }
+}    
+ ~~~~ [trailing whitespace]
+const template = ` 
+                  ~ [trailing whitespace]
+I have trailing whitespace  
+                          ~~ [trailing whitespace]
+`;
+// single line comment without trailing whitespace
+// single line comment with trailing whitespace   
+                                               ~~~ [trailing whitespace]
+ /* single line multiline comment */
+/* whitespace after comment */ 
+                              ~ [trailing whitespace]
+/* first line has trailing whitespace  
+                                     ~~ [trailing whitespace]
+   second line is ok
+   last line is not checked         */
+/*
+ */
+
+/**
+ * JSDoc comment with trailing whitespace 
+                                         ~ [trailing whitespace]
+ * 
+  ~ [trailing whitespace]
+ */
+
+/***
+ * not a JSDoc comment 
+                      ~ [trailing whitespace]
+ * 
+  ~ [trailing whitespace]
+ */
+
+// following line checks for trailing whitespace before EOF
+

test/rules/no-trailing-whitespace/skip-blank-lines/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "no-trailing-whitespace": [true, "ignore-blank-lines"]
+  }
+}