diff --git a/__tests__/HierarchicalSingleEvent.test.ts b/__tests__/HierarchicalSingleEvent.test.ts
index 45e7b998..77eb8034 100644
--- a/__tests__/HierarchicalSingleEvent.test.ts
+++ b/__tests__/HierarchicalSingleEvent.test.ts
@@ -4,7 +4,8 @@ import {
   Parameter,
   OutPort,
   InPort,
-  TimeValue
+  TimeValue,
+  CanConnectResult
 } from "../src/core/internal";
 
 import {SingleEvent} from "../src/share/SingleEvent";
@@ -93,7 +94,7 @@ describe("HierarchicalSingleEvent", function () {
         seTest.seContainer.child.o,
         seTest.logContainer.child.i
       )
-    ).toBe(false);
+    ).toBe(CanConnectResult.NOT_IN_SCOPE);
 
     seTest._start();
   });
diff --git a/__tests__/SingleEvent.test.ts b/__tests__/SingleEvent.test.ts
index ac89fb1f..ab49c55f 100644
--- a/__tests__/SingleEvent.test.ts
+++ b/__tests__/SingleEvent.test.ts
@@ -32,12 +32,8 @@ describe("SingleEvent", function () {
     expect(expect(seTest.singleEvent).toBeInstanceOf(SingleEvent));
     expect(expect(seTest.logger).toBeInstanceOf(Logger));
 
-    expect(function () {
-      seTest.canConnect(seTest.singleEvent.o, seTest.logger.i);
-    }).toThrow(new Error("Destination port is already occupied."));
-    expect(seTest.canConnect(seTest.logger.i, seTest.singleEvent.o)).toBe(
-      false
-    );
+    expect(seTest.canConnect(seTest.singleEvent.o, seTest.logger.i)).toBeTruthy();
+    expect(seTest.canConnect(seTest.logger.i, seTest.singleEvent.o)).toBeTruthy();
 
     seTest._start();
   });
diff --git a/__tests__/connection.test.ts b/__tests__/connection.test.ts
index 3d8725e3..4798b7bc 100644
--- a/__tests__/connection.test.ts
+++ b/__tests__/connection.test.ts
@@ -5,7 +5,8 @@ import {
   OutPort,
   InPort,
   TimeUnit,
-  TimeValue
+  TimeValue,
+  CanConnectResult
 } from "../src/core/internal";
 
 describe("Check canConnect", () => {
@@ -30,19 +31,19 @@ describe("Check canConnect", () => {
 
       it("canConnect success out->in", () => {
         expect(this.canConnect(this.source.out, this.destination.in)).toBe(
-          true
+          CanConnectResult.SUCCESS
         );
       });
 
       it("canConnect success out->out", () => {
         expect(this.canConnect(this.source.out, this.destination.out)).toBe(
-          true
+          CanConnectResult.SUCCESS
         );
       });
 
       it("canConnect failure", () => {
         expect(this.canConnect(this.destination.in, this.source.out)).toBe(
-          false
+          CanConnectResult.NOT_IN_SCOPE
         );
       });
     }
diff --git a/__tests__/hierarchy.ts b/__tests__/hierarchy.ts
index ec7fda22..0515e861 100644
--- a/__tests__/hierarchy.ts
+++ b/__tests__/hierarchy.ts
@@ -1,4 +1,4 @@
-import {Reactor, App, InPort, OutPort} from "../src/core/internal";
+import {Reactor, App, InPort, OutPort, CanConnectResult} from "../src/core/internal";
 
 class InOut extends Reactor {
   a = new InPort<string>(this);
@@ -36,65 +36,57 @@ describe("Container to Contained", () => {
   it("testing canConnect", () => {
     expect(
       app.container.canConnect(app.container.a, app.container.contained.a)
-    ).toBe(true);
+    ).toBe(CanConnectResult.SUCCESS);
     expect(
       app.container.canConnect(app.container.contained.a, app.container.a)
-    ).toBe(false);
+    ).toBe(CanConnectResult.NOT_IN_SCOPE);
     expect(
       app.container.canConnect(
         app.container.a,
         app.container.b
       )
-    ).toBe(true);
+    ).toBe(CanConnectResult.SUCCESS);
     expect(
       app.container.canConnect(
         app.container.contained.a,
         app.container.contained.b
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.canConnect(
         app.container.contained.b,
         app.container.contained.a
       )
-    ).toBe(true);
+    ).toBeFalsy();
 
     expect(
       app.container.canConnect(app.container.a, app.container.contained.b)
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.canConnect(app.container.contained.b, app.container.a)
-    ).toBe(false);
+    ).toBeTruthy();
 
     expect(
       app.container.canConnect(app.container.b, app.container.contained.a)
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.canConnect(app.container.contained.a, app.container.b)
-    ).toBe(false);
+    ).toBeTruthy();
 
     expect(
       app.container.canConnect(app.container.b, app.container.contained.b)
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.canConnect(app.container.contained.b, app.container.b)
-    ).toBe(true);
-
-    expect(app.container.canConnect(app.container.contained.a, app.foo.a)).toBe(
-      false
-    );
-    expect(app.container.canConnect(app.container.contained.a, app.foo.b)).toBe(
-      false
-    );
-    expect(app.container.canConnect(app.foo.a, app.container.contained.a)).toBe(
-      false
-    );
-    expect(app.container.canConnect(app.foo.a, app.container.contained.a)).toBe(
-      false
-    );
-
-    expect(app.container.canConnect(app.foo.a, app.container.b)).toBe(false);
-    expect(app.container.canConnect(app.foo.a, app.container.a)).toBe(false);
+    ).toBeFalsy();
+
+    expect(app.container.canConnect(app.container.contained.a, app.foo.a)).toBeTruthy();
+    expect(app.container.canConnect(app.container.contained.a, app.foo.b)).toBeTruthy();
+    expect(app.container.canConnect(app.foo.a, app.container.contained.a)).toBeTruthy();
+    expect(app.container.canConnect(app.foo.a, app.container.contained.a)).toBeTruthy();
+
+    expect(app.container.canConnect(app.foo.a, app.container.b)).toBeTruthy();
+    expect(app.container.canConnect(app.foo.a, app.container.a)).toBeTruthy();
 
     // expect(app.container.contained).toBeDefined();
 
@@ -104,49 +96,49 @@ describe("Container to Contained", () => {
         app.container.contained.containedAgain.a,
         app.container.contained.a
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.b,
         app.container.contained.b
       )
-    ).toBe(true);
+    ).toBeFalsy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.a,
         app.container.a
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.b,
         app.container.b
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.a,
         app.foo.a
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.b,
         app.foo.b
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.a,
         app.foo.a
       )
-    ).toBe(false);
+    ).toBeTruthy();
     expect(
       app.container.contained.canConnect(
         app.container.contained.containedAgain.b,
         app.foo.b
       )
-    ).toBe(false);
+    ).toBeTruthy();
     // }
   });
 });