feat(no-misused-observables): interface declarations

Author: JasonWeinzierl

src/etc/get-type-services.ts

@@ -44,6 +44,10 @@ export function getTypeServices<
       || ts.isMethodSignature(tsNode)
     ) {
       tsTypeNode = tsNode.type;
+    } else if (
+      ts.isPropertySignature(tsNode)
+    ) {
+      // TODO(#66): this doesn't work for functions assigned to class properties, variables, params.
     }
     return Boolean(
       tsTypeNode

src/rules/no-misused-observables.ts

@@ -53,7 +53,7 @@ export const noMisusedObservablesRule = ruleCreator({
       JSXAttribute: checkJSXAttribute,
       ClassDeclaration: checkClassLikeOrInterfaceNode,
       ClassExpression: checkClassLikeOrInterfaceNode,
-      // TSInterfaceDeclaration: checkClassLikeOrInterfaceNode,
+      TSInterfaceDeclaration: checkClassLikeOrInterfaceNode,
       // Property: checkProperty,
       // ReturnStatement: checkReturnStatement,
       // AssignmentExpression: checkAssignment,

tests/rules/no-misused-observables.test.ts

@@ -84,6 +84,10 @@ ruleTester({ types: true }).run('no-misused-observables', noMisusedObservablesRu
         const Baz = class extends Foo {
           foo(): Observable<number> { return of(42); }
         }
+
+        interface Qux extends Foo {
+          foo(): Observable<number>;
+        }
       `,
       options: [{ checksVoidReturn: false }],
     },
@@ -375,6 +379,190 @@ ruleTester({ types: true }).run('no-misused-observables', noMisusedObservablesRu
         }
       `,
     ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends class
+        import { Observable } from "rxjs";
+
+        class Foo {
+          foo(): void {}
+        }
+
+        interface Bar extends Foo {
+          foo(): Observable<number>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Foo" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends abstract
+        import { Observable } from "rxjs";
+
+        abstract class Foo {
+          abstract foo(): void;
+        }
+
+        interface Bar extends Foo {
+          foo(): Observable<number>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Foo" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends interface
+        import { Observable } from "rxjs";
+
+        interface Foo {
+          foo(): void;
+        }
+
+        interface Bar extends Foo {
+          foo(): Observable<number>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Foo" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends conditional type
+        import { Observable } from "rxjs";
+
+        type Foo<IsRx extends boolean = true> = IsRx extends true
+          ? { foo(): Observable<void> }
+          : { foo(): void };
+
+        interface Bar extends Foo<false> {
+          foo(): Observable<void>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "{ foo(): void; }" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends multiple
+        import { Observable } from "rxjs";
+
+        interface Foo {
+          foo(): void;
+        }
+
+        interface Bar {
+          foo(): void;
+        }
+
+        interface Baz extends Foo, Bar {
+          foo(): Observable<void>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Foo" }]
+          ~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Bar" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends multiple classes
+        import { Observable } from "rxjs";
+
+        class Foo {
+          foo(): void {}
+        }
+
+        class Bar {
+          foo(): void {}
+        }
+
+        interface Baz extends Foo, Bar {
+          foo(): Observable<void>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Foo" }]
+          ~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Bar" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends typeof class
+        import { Observable } from "rxjs";
+
+        const Foo = class {
+          foo(): void {}
+        }
+
+        type Bar = typeof Foo;
+
+        interface Baz extends Bar {
+          foo(): Observable<void>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "typeof Foo" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends function, index, constructor
+        import { Observable } from "rxjs";
+
+        interface Foo {
+          (): void;
+          (arg: string): void;
+          new (): void;
+          [key: string]: () => void;
+          [key: number]: () => void;
+          myMethod(): void;
+        }
+
+        interface Bar extends Foo {
+          (): Observable<void>;
+          (arg: string): Observable<void>;
+          new (): Observable<void>;
+          [key: string]: () => Observable<void>;
+          [key: number]: () => Observable<void>;
+          myMethod(): Observable<void>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Foo" }]
+        }
+      `,
+    ),
+    fromFixture(
+      stripIndent`
+        // void return inherited method; interface; extends multiple function, index, constructor
+        import { Observable } from "rxjs";
+
+        interface Foo {
+          (): void;
+          (arg: string): void;
+        }
+
+        interface Bar {
+          [key: string]: () => void;
+          [key: number]: () => void;
+        }
+
+        interface Baz {
+          new (): void;
+          new (arg: string): void;
+        }
+
+        interface Qux {
+          doSyncThing(): void;
+          doOtherSyncThing(): void;
+          syncMethodProperty: () => void;
+        }
+
+        interface Quux extends Foo, Bar, Baz, Qux {
+          (): void;
+          (arg: string): Observable<void>;
+          new (): void;
+          new (arg: string): void;
+          [key: string]: () => Observable<void>;
+          [key: number]: () => void;
+          doSyncThing(): Observable<void>;
+          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Qux" }]
+          doRxThing(): Observable<void>;
+          syncMethodProperty: () => Observable<void>;
+          //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [forbiddenVoidReturnInheritedMethod { "heritageTypeName": "Qux" }]
+          // TODO(#66): couldReturnType doesn't work for properties.
+        }
+      `,
+    ),
     // #endregion invalid; void return inherited method
     // #region invalid; spread
     fromFixture(