fix: Added more thorough checks to RemoteData type guards

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ngx-remotedata",
-  "version": "6.0.0",
+  "version": "6.0.1",
   "description": "RemoteData: Slaying a UI Antipattern with Angular",
   "repository": {
     "type": "git",

projects/lib/src/lib/remote-data.spec.ts

@@ -10,9 +10,19 @@ import {
   mapFailure,
   isFailure,
   isInProgress,
-  chain
+  chain,
+  isNotAsked,
+  isSuccess,
+  isRemoteData
 } from './remote-data';
 
+interface RemoteDataGuardsTestObj {
+  name: string;
+  fn: (rd: RemoteData<any, any>) => boolean;
+  truth: RemoteData<any, any>;
+  falses: any[];
+}
+
 describe('RemoteData', () => {
   describe('notAsked', () => {
     it('should have a "NotAsked" tag', () => {
@@ -138,4 +148,48 @@ describe('RemoteData', () => {
       expect(ageResult).toEqual(failure('-3  is an invalid age'));
     });
   });
+
+  describe('Type Guard', () => {
+    ([
+      {
+        name: 'isNotAsked',
+        fn: isNotAsked,
+        truth: notAsked(),
+        falses: [success('hola'), null, undefined, 'hola', {}]
+      },
+      {
+        name: 'isSuccess',
+        fn: isSuccess,
+        truth: success(1),
+        falses: [notAsked(), null, undefined, 'hola', {}]
+      },
+      {
+        name: 'isFailure',
+        fn: isFailure,
+        truth: failure('error!', 9),
+        falses: [success(9), null, undefined, 77, NaN]
+      },
+      {
+        name: 'isInProgress',
+        fn: isInProgress,
+        truth: inProgress(true),
+        falses: [failure('error!'), null, undefined, true, []]
+      },
+      {
+        name: 'isRemoteData',
+        fn: isRemoteData,
+        truth: notAsked(),
+        falses: [null, undefined, true, [], NaN, 8]
+      }
+    ] as RemoteDataGuardsTestObj[]).forEach(test => {
+      describe(test.name, () => {
+        it('should be true', () => {
+          expect(test.fn(test.truth)).toBe(true);
+        });
+        it('should be false', () => {
+          test.falses.forEach(val => expect(test.fn(val)).toBe(false));
+        });
+      });
+    });
+  });
 });

projects/lib/src/lib/remote-data.ts

@@ -57,6 +57,7 @@ export const isNotAsked = <T, E>(value: unknown): value is NotAsked => {
   return (
     value !== null &&
     value !== undefined &&
+    (value as object).hasOwnProperty('tag') &&
     (value as RemoteData<T, E>).tag === 'NotAsked'
   );
 };
@@ -65,6 +66,7 @@ export const isInProgress = <T, E>(value: unknown): value is InProgress<T> => {
   return (
     value !== null &&
     value !== undefined &&
+    (value as object).hasOwnProperty('tag') &&
     (value as RemoteData<T, E>).tag === 'InProgress'
   );
 };
@@ -73,6 +75,7 @@ export const isFailure = <T, E>(value: unknown): value is Failure<E, T> => {
   return (
     value !== null &&
     value !== undefined &&
+    (value as object).hasOwnProperty('tag') &&
     (value as RemoteData<T, E>).tag === 'Failure'
   );
 };
@@ -81,20 +84,24 @@ export const isSuccess = <T, E>(value: unknown): value is Success<T> => {
   return (
     value !== null &&
     value !== undefined &&
+    (value as object).hasOwnProperty('tag') &&
     (value as RemoteData<T, E>).tag === 'Success'
   );
 };
 
 export const isRemoteData = <T, E = DefaultError>(
   value: unknown
 ): value is RemoteData<T, E> => {
+  const hasRemoteDataTag = (tag: RemoteData<any, any>['tag']) =>
+    tag === 'NotAsked' ||
+    tag === 'InProgress' ||
+    tag === 'Success' ||
+    tag === 'Failure';
   return (
-    (value !== null &&
-      value !== undefined &&
-      (value as RemoteData<T, E>).tag === 'NotAsked') ||
-    (value as RemoteData<T, E>).tag === 'InProgress' ||
-    (value as RemoteData<T, E>).tag === 'Success' ||
-    (value as RemoteData<T, E>).tag === 'Failure'
+    value !== null &&
+    value !== undefined &&
+    (value as object).hasOwnProperty('tag') &&
+    hasRemoteDataTag((value as RemoteData<T, E>).tag)
   );
 };