Add a test upstreams button

Closes #321

client/src/actions/index.js

@@ -420,3 +420,36 @@ export const setUpstream = url => async (dispatch) => {
         dispatch(setUpstreamFailure());
     }
 };
+
+export const testUpstreamRequest = createAction('TEST_UPSTREAM_REQUEST');
+export const testUpstreamFailure = createAction('TEST_UPSTREAM_FAILURE');
+export const testUpstreamSuccess = createAction('TEST_UPSTREAM_SUCCESS');
+
+export const testUpstream = servers => async (dispatch) => {
+    dispatch(testUpstreamRequest());
+    try {
+        if (servers.length > 0) {
+            const upstreamResponse = await apiClient.testUpstream(servers);
+
+            const testMessages = Object.keys(upstreamResponse).map((key) => {
+                const message = upstreamResponse[key];
+                if (message !== 'OK') {
+                    dispatch(addErrorToast({ error: `Server "${key}": could not be used, please check that you've written it correctly` }));
+                }
+                return message;
+            });
+
+            if (testMessages.every(message => message === testMessages[0])) {
+                dispatch(addSuccessToast('All servers is OK'));
+            }
+
+            dispatch(testUpstreamSuccess());
+        } else {
+            dispatch(addErrorToast({ error: 'No servers specified' }));
+            dispatch(testUpstreamFailure());
+        }
+    } catch (error) {
+        dispatch(addErrorToast({ error }));
+        dispatch(testUpstreamFailure());
+    }
+};