new rule: initialize-static-property

baselines/packages/mimir/api/packlist.txt

@@ -28,6 +28,9 @@ src/rules/delete-only-optional-property.js.map
 src/rules/generator-require-yield.d.ts
 src/rules/generator-require-yield.js
 src/rules/generator-require-yield.js.map
+src/rules/initialize-static-property.d.ts
+src/rules/initialize-static-property.js
+src/rules/initialize-static-property.js.map
 src/rules/new-parens.d.ts
 src/rules/new-parens.js
 src/rules/new-parens.js.map

baselines/packages/mimir/api/src/rules/initialize-static-property.d.ts

@@ -0,0 +1,4 @@
+import { AbstractRule } from '@fimbul/ymir';
+export declare class Rule extends AbstractRule {
+    apply(): void;
+}

packages/mimir/recommended.yaml

@@ -6,6 +6,7 @@ rules:
   ban-dom-globals: error
   delete-only-optional-property: error
   generator-require-yield: error
+  initialize-static-property: error
   new-parens: error
   no-case-declaration: error
   no-debugger: error

packages/mimir/src/rules/initialize-static-property.ts

@@ -0,0 +1,28 @@
+import { AbstractRule, excludeDeclarationFiles } from '@fimbul/ymir';
+import * as ts from 'typescript';
+import { WrappedAst, getWrappedNodeAtPosition, isPropertyDeclaration, isStatementInAmbientContext, hasModifier } from 'tsutils';
+
+@excludeDeclarationFiles
+export class Rule extends AbstractRule {
+    public apply() {
+        let wrappedAst: WrappedAst | undefined;
+        const {text} = this.sourceFile;
+        const re = /\bstatic\b/g;
+
+        for (let match = re.exec(text); match !== null; match = re.exec(text)) {
+            const {node} = getWrappedNodeAtPosition(wrappedAst || (wrappedAst = this.context.getWrappedAst()), match.index)!;
+            if (node.kind !== ts.SyntaxKind.StaticKeyword)
+                continue;
+            const member = node.parent!;
+            if (
+                isPropertyDeclaration(member) &&
+                member.initializer === undefined &&
+                member.questionToken === undefined &&
+                // TODO move to tsutils as isAmbientPropertyDeclaration
+                !hasModifier(member.modifiers, ts.SyntaxKind.DeclareKeyword) &&
+                !(member.parent!.kind === ts.SyntaxKind.ClassDeclaration && isStatementInAmbientContext(member.parent!))
+            )
+                this.addFindingAtNode(member.name, "Non-optional 'static' property must be initialized.");
+        }
+    }
+}