Unit test ExportDialog (#7619)

* add test ids to dialog buttons

Signed-off-by: Kerry Archibald <kerrya@element.io>

* unit test ExportDialog

Signed-off-by: Kerry Archibald <kerrya@element.io>

* remove extra snapshot

Signed-off-by: Kerry Archibald <kerrya@element.io>

* fix bad snapshots

Signed-off-by: Kerry Archibald <kerrya@element.io>

* remove wrappers from snapshot

Signed-off-by: Kerry Archibald <kerrya@element.io>

src/components/views/elements/DialogButtons.tsx

@@ -83,6 +83,7 @@ export default class DialogButtons extends React.Component<IProps> {
             cancelButton = <button
                 // important: the default type is 'submit' and this button comes before the
                 // primary in the DOM so will get form submissions unless we make it not a submit.
+                data-test-id="dialog-cancel-button"
                 type="button"
                 onClick={this.onCancelClick}
                 className={this.props.cancelButtonClass}
@@ -103,6 +104,7 @@ export default class DialogButtons extends React.Component<IProps> {
                 { cancelButton }
                 { this.props.children }
                 <button type={this.props.primaryIsSubmit ? 'submit' : 'button'}
+                    data-test-id="dialog-primary-button"
                     className={primaryButtonClassName}
                     onClick={this.props.onPrimaryButtonClick}
                     autoFocus={this.props.focus}