feat: interface sort keys rule

src/interfaceSortKeysRule.ts

@@ -0,0 +1,50 @@
+import * as Lint from "tslint";
+import {Identifier} from "typescript";
+import * as ts from "typescript";
+
+class InterfaceSortKeysRule extends Lint.RuleWalker {
+  constructor(
+    sourceFile: ts.SourceFile,
+    options: Lint.IOptions
+  ) {
+    super(sourceFile, options);
+  }
+
+  public visitInterfaceDeclaration(node: ts.InterfaceDeclaration): void {
+    super.visitInterfaceDeclaration(node);
+    this.checkAlphabetical(node);
+  }
+
+  public visitTypeLiteral(node: ts.TypeLiteralNode): void {
+    super.visitTypeLiteral(node);
+    this.checkAlphabetical(node);
+  }
+
+  private checkAlphabetical(node: ts.InterfaceDeclaration | ts.TypeLiteralNode): void {
+    const properties = node.members.map((member) => (member.name as Identifier).escapedText.toString());
+    const unsortedIndex = this.getUnsortedIndex(properties);
+    if (unsortedIndex !== -1) {
+      this.addFailureAtNode(
+        node.members[unsortedIndex].name as Identifier,
+        `The key '${(node.members[unsortedIndex].name as Identifier).escapedText}' is not sorted alphabetically`
+      );
+    }
+  }
+
+  private getUnsortedIndex(strs: string[], startIndex: number = 0): number {
+    if (strs.length < 2 || strs.length === startIndex + 1) {
+      return -1;
+    }
+    if (strs[startIndex] > strs[startIndex + 1]) {
+      return startIndex;
+    }
+    return this.getUnsortedIndex(strs, startIndex + 1);
+  }
+}
+
+// tslint:disable-next-line:export-name max-classes-per-file
+export class Rule extends Lint.Rules.AbstractRule {
+  public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+    return this.applyWithWalker(new InterfaceSortKeysRule(sourceFile, this.getOptions()));
+  }
+}

test/rules/interface-sort-keys/default/test.ts.lint

@@ -0,0 +1,49 @@
+export interface IAlphabet {
+  aaa: string;
+  bbb: string;
+  ccc: string;
+  cccAaa: string;
+  cccc: string;
+  ddd: {
+    dddAaa: string;
+    dddBbb: string;
+  }
+}
+
+export interface IAlphabet {
+  aaa: string;
+  bbb: string;
+  cccAaa: string;
+  ~~~~~~           [The key 'cccAaa' is not sorted alphabetically]
+  ccc: string;
+  cccc: string;
+}
+
+export interface IAlphabet {
+  aaa: string;
+  bbb: string;
+  ccc: string;
+  cccc: string;
+  ~~~~           [The key 'cccc' is not sorted alphabetically]
+  cccAaa: string;
+}
+
+export interface IAlphabet {
+  aaa: string;
+  ddd: {
+  ~~~     [The key 'ddd' is not sorted alphabetically]
+    dddAaa: string;
+    dddBbb: string;
+  }
+  bbb: string;
+}
+
+export interface IAlphabet {
+  aaa: string;
+  bbb: string;
+  ddd: {
+    dddBbb: string;
+    ~~~~~~         [The key 'dddBbb' is not sorted alphabetically]
+    dddAaa: string;
+  }
+}

test/rules/interface-sort-keys/default/tslint.json

@@ -0,0 +1,8 @@
+{
+  "rulesDirectory": [
+    "../../../../lib"
+  ],
+  "rules": {
+    "interface-sort-keys": true
+  }
+}