Fix no-trailing-whitespace for comments and EOF (#2060)

Detect trailing whitespace in comments.
Detect trailing whitespace before EOF.
Add fixer.

Fixes: #2049

src/rules/noTrailingWhitespaceRule.ts

@@ -26,6 +26,7 @@ export class Rule extends Lint.Rules.AbstractRule {
         description: "Disallows trailing whitespace at the end of a line.",
         rationale: "Keeps version control diffs clean as it prevents accidental whitespace from being committed.",
         optionsDescription: "Not configurable.",
+        hasFix: true,
         options: null,
         optionExamples: ["true"],
         type: "maintainability",
@@ -44,18 +45,52 @@ class NoTrailingWhitespaceWalker extends Lint.RuleWalker {
     public visitSourceFile(node: ts.SourceFile) {
         let lastSeenWasWhitespace = false;
         let lastSeenWhitespacePosition = 0;
-        Lint.forEachToken(node, false, (_text, kind, pos) => {
-            if (kind === ts.SyntaxKind.NewLineTrivia) {
+        Lint.forEachToken(node, false, (fullText, kind, pos) => {
+            if (kind === ts.SyntaxKind.NewLineTrivia || kind === ts.SyntaxKind.EndOfFileToken) {
                 if (lastSeenWasWhitespace) {
-                    this.addFailureFromStartToEnd(lastSeenWhitespacePosition, pos.tokenStart, Rule.FAILURE_STRING);
+                    this.reportFailure(lastSeenWhitespacePosition, pos.tokenStart);
                 }
                 lastSeenWasWhitespace = false;
             } else if (kind === ts.SyntaxKind.WhitespaceTrivia) {
                 lastSeenWasWhitespace = true;
                 lastSeenWhitespacePosition = pos.tokenStart;
             } else {
+                if (kind === ts.SyntaxKind.SingleLineCommentTrivia) {
+                    const commentText = fullText.substring(pos.tokenStart + 2, pos.end);
+                    const match = /\s+$/.exec(commentText);
+                    if (match !== null) {
+                        this.reportFailure(pos.end - match[0].length, pos.end);
+                    }
+                } else if (kind === ts.SyntaxKind.MultiLineCommentTrivia) {
+                    let startPos = pos.tokenStart + 2;
+                    const commentText = fullText.substring(startPos, pos.end - 2);
+                    const lines = commentText.split("\n");
+                    // we don't want to check the content of the last comment line, as it is always followed by */
+                    const len = lines.length - 1;
+                    for (let i = 0; i < len; ++i) {
+                        let line = lines[i];
+                        // remove carriage return at the end, it is does not account to trailing whitespace
+                        if (line.endsWith("\r")) {
+                            line = line.substr(0, line.length - 1);
+                        }
+                        const start = line.search(/\s+$/);
+                        if (start !== -1) {
+                            this.reportFailure(startPos + start, startPos + line.length);
+                        }
+                        startPos += lines[i].length + 1;
+                    }
+                }
                 lastSeenWasWhitespace = false;
             }
         });
     }
+
+    private reportFailure(start: number, end: number) {
+        this.addFailureFromStartToEnd(
+            start,
+            end,
+            Rule.FAILURE_STRING,
+            this.createFix(this.deleteText(start, end - start)),
+        );
+    }
 }

test/rules/no-trailing-whitespace/test.js.fix

@@ -0,0 +1,10 @@
+class Clazz {
+    public funcxion() {
+        console.log("test")   ;
+    }
+
+
+    private foobar() {
+    }
+}
+

test/rules/no-trailing-whitespace/test.ts.fix

@@ -0,0 +1,20 @@
+class Clazz {
+    public funcxion() {
+        console.log("test")   ;
+    }
+
+
+    private foobar() {
+    }
+}
+// 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         */
+/*
+ */
+
+// following line checks for trailing whitespace before EOF

test/rules/no-trailing-whitespace/test.ts.lint

@@ -1,16 +1,30 @@
 class Clazz {
     public funcxion() {    
-                       ~~~~ [0]
+                       ~~~~ [trailing whitespace]
         console.log("test")   ;    
-                               ~~~~ [0]
+                               ~~~~ [trailing whitespace]
     }
 
-~~~~ [0]
+~~~~ [trailing whitespace]
 
-~~~~ [0]
+~~~~ [trailing whitespace]
     private foobar() {
     }
 }    
- ~~~~ [0]
+ ~~~~ [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         */
+/*
+ */
 
-[0]: trailing whitespace
+// following line checks for trailing whitespace before EOF
+
+~~~ [trailing whitespace]