test: move Image to RTL (react-bootstrap#6222)

* Delete AlertSpec.js

* add AlertSpec.tsx

* Delete ImageSpec.js

* Create ImageSpec.tsx

Author: saltybuckets

test/ImageSpec.js

@@ -0,0 +1,55 @@
+import { render } from '@testing-library/react';
+
+import Image from '../src/Image';
+
+describe('Image', () => {
+  it('should be an image', () => {
+    
+    const { getByTestId } = render(
+      <Image data-testid="test-image" />,
+    );
+    getByTestId('test-image').tagName.toLowerCase().should.equal('img');
+  });
+
+  it('should provide src and alt prop', () => {
+    const { getByTestId } = render(
+      <Image data-testid="test-image" src="image.jpg" alt="this is alt" />,
+    );
+    getByTestId('test-image').getAttribute('src')!.should.equal('image.jpg');
+    getByTestId('test-image').getAttribute('alt')!.should.equal('this is alt');
+
+  });
+
+  it('should have correct class when fluid prop is set', () => {
+    const { getByTestId } = render(<Image data-testid="test-image" fluid />);
+    getByTestId('test-image').classList.contains('img-fluid').should.be.true; 
+  });
+
+  it('should not override class when rounded prop is set', () => {
+    const { getByTestId } = render(
+      <Image data-testid="test-image" fluid rounded />,
+    );
+    getByTestId('test-image').classList.contains('img-fluid').should.be.true;
+    getByTestId('test-image').classList.contains('rounded').should.be.true;
+
+  });
+
+  it('should have correct class when rounded prop is set', () => {
+    const { getByTestId } = render(<Image data-testid="test-image" rounded />);
+    getByTestId('test-image').classList.contains('rounded').should.be.true;
+  });
+
+  it('should have correct class when roundedCircle prop is set', () => {
+    const { getByTestId } = render(
+      <Image data-testid="test-image" roundedCircle />,
+    );
+    getByTestId('test-image').classList.contains('rounded-circle').should.be.true;
+
+  });
+
+  it('should have correct class when thumbnail prop is set', () => {
+    const { getByTestId } = render(<Image data-testid="test-image" thumbnail />);
+    getByTestId('test-image').classList.contains('img-thumbnail').should.be.true;
+    
+  });
+});