[new-fixer] file-header rule (palantir#3475)

src/rules/fileHeaderRule.ts

@@ -23,11 +23,26 @@ export class Rule extends Lint.Rules.AbstractRule {
     public static metadata: Lint.IRuleMetadata = {
         ruleName: "file-header",
         description: "Enforces a certain header comment for all files, matched by a regular expression.",
-        optionsDescription: "Regular expression to match the header.",
+        optionsDescription: Lint.Utils.dedent`
+            The first option, which is mandatory, is a regular expression that all headers should match.
+            The second argument, which is optional, is a string that should be inserted as a header comment
+            if fixing is enabled and no header that matches the first argument is found.`,
         options: {
-            type: "string",
+            type: "array",
+            items: [
+                {
+                    type: "string",
+                },
+                {
+                    type: "string",
+                },
+            ],
+            additionalItems: false,
+            minLength: 1,
+            maxLength: 2,
         },
-        optionExamples: [[true, "Copyright \\d{4}"]],
+        optionExamples: [[true, "Copyright \\d{4}", "Copyright 2017"]],
+        hasFix: true,
         type: "style",
         typescriptOnly: false,
     };
@@ -37,19 +52,42 @@ export class Rule extends Lint.Rules.AbstractRule {
 
     public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
         const { text } = sourceFile;
+        const headerFormat = new RegExp(this.ruleArguments[0] as string);
+        const textToInsert = this.ruleArguments[1] as string | undefined;
+
         // ignore shebang if it exists
         let offset = text.startsWith("#!") ? text.indexOf("\n") : 0;
         // returns the text of the first comment or undefined
         const commentText = ts.forEachLeadingCommentRange(
             text,
             offset,
             (pos, end, kind) => text.substring(pos + 2, kind === ts.SyntaxKind.SingleLineCommentTrivia ? end : end - 2));
-        if (commentText === undefined || !new RegExp(this.ruleArguments[0] as string).test(commentText)) {
-            if (offset !== 0) {
+
+        if (commentText === undefined || !headerFormat.test(commentText)) {
+            const isErrorAtStart = offset === 0;
+            if (!isErrorAtStart) {
                 ++offset; // show warning in next line after shebang
             }
-            return [new Lint.RuleFailure(sourceFile, offset, offset, Rule.FAILURE_STRING, this.ruleName)];
+            const leadingNewlines = isErrorAtStart ? 0 : 1;
+            const trailingNewlines = isErrorAtStart ? 2 : 1;
+
+            const fix = textToInsert !== undefined
+                ? Lint.Replacement.appendText(offset, this.createComment(sourceFile, textToInsert, leadingNewlines, trailingNewlines))
+                : undefined;
+            return [new Lint.RuleFailure(sourceFile, offset, offset, Rule.FAILURE_STRING, this.ruleName, fix)];
         }
         return [];
     }
+
+    private createComment(sourceFile: ts.SourceFile, commentText: string, leadingNewlines = 1, trailingNewlines = 1) {
+        const maybeCarriageReturn = sourceFile.text[sourceFile.getLineEndOfPosition(0)] === "\r" ? "\r" : "";
+        const lineEnding = `${maybeCarriageReturn}\n`;
+        return lineEnding.repeat(leadingNewlines) + [
+            "/*",
+            // split on both types of line endings in case users just typed "\n" in their configs
+            // but are working in files with \r\n line endings
+            ...commentText.split(/\r?\n/g).map((line) => ` * ${line}`),
+            " */",
+        ].join(lineEnding) + lineEnding.repeat(trailingNewlines);
+    }
 }

test/rules/file-header/bad-shebang/test.ts.fix

@@ -0,0 +1,21 @@
+#!/usr/bin/env node
+
+/*
+ * Good header 2
+ */
+
+/*
+ * Bad header 3
+ */
+
+export class A {
+    public x = 1;
+
+    public B() {
+        return 2;
+    }
+}
+
+/*
+ * Good header 4
+ */

test/rules/file-header/bad-shebang/tslint.json

@@ -1,5 +1,5 @@
 {
     "rules": {
-        "file-header": [true, "Good header \\d"]
+        "file-header": [true, "Good header \\d", "Good header 2"]
     }
 }

test/rules/file-header/bad-single-line/test.ts.fix

@@ -0,0 +1,17 @@
+/*
+ * Good header 2
+ */
+
+// Bad header 1
+
+export class A {
+    public x = 1;
+
+    public B() {
+        return 2;
+    }
+}
+
+/*
+ * Good header 2
+ */

test/rules/file-header/bad-single-line/tslint.json

@@ -1,5 +1,5 @@
 {
     "rules": {
-        "file-header": [true, "Good header \\d"]
+        "file-header": [true, "Good header \\d", "Good header 2"]
     }
 }

test/rules/file-header/bad-use-strict/test.ts.fix

@@ -0,0 +1,21 @@
+/*
+ * Good header 2
+ */
+
+"use strict";
+
+/*
+ * Bad header 5
+ */
+
+export class A {
+    public x = 1;
+
+    public B() {
+        return 2;
+    }
+}
+
+/*
+ * Good header 6
+ */

test/rules/file-header/bad-use-strict/tslint.json

@@ -1,5 +1,5 @@
 {
     "rules": {
-        "file-header": [true, "Good header \\d"]
+        "file-header": [true, "Good header \\d", "Good header 2"]
     }
 }

test/rules/file-header/bad/test.ts.fix

@@ -0,0 +1,19 @@
+/*
+ * Good header 2
+ */
+
+/*
+ * Bad header 1
+ */
+
+export class A {
+    public x = 1;
+
+    public B() {
+        return 2;
+    }
+}
+
+/*
+ * Good header 2
+ */

test/rules/file-header/bad/tslint.json

@@ -1,5 +1,5 @@
 {
     "rules": {
-        "file-header": [true, "Good header \\d"]
+        "file-header": [true, "Good header \\d", "Good header 2"]
     }
 }

test/rules/file-header/good/test.ts.fix

@@ -0,0 +1,12 @@
+
+/*
+ * Good header 1
+ */
+
+export class A {
+    public x = 1;
+
+    public B() {
+        return 2;
+    }
+}