Added test for url state in Explore

public/app/features/explore/Wrapper.test.tsx

+import { serializeStateToUrlParam, parseUrlState } from './Wrapper';
+import { DEFAULT_RANGE } from './TimePicker';
+import { ExploreState } from './Explore';
+
+const DEFAULT_EXPLORE_STATE: ExploreState = {
+  datasource: null,
+  datasourceError: null,
+  datasourceLoading: null,
+  datasourceMissing: false,
+  datasourceName: '',
+  graphResult: null,
+  history: [],
+  latency: 0,
+  loading: false,
+  logsResult: null,
+  queries: [],
+  queryErrors: [],
+  queryHints: [],
+  range: DEFAULT_RANGE,
+  requestOptions: null,
+  showingGraph: true,
+  showingLogs: true,
+  showingTable: true,
+  supportsGraph: null,
+  supportsLogs: null,
+  supportsTable: null,
+  tableResult: null,
+};
+
+describe('Wrapper state functions', () => {
+  describe('parseUrlState', () => {
+    it('returns default state on empty string', () => {
+      expect(parseUrlState('')).toMatchObject({
+        datasource: null,
+        queries: [],
+        range: DEFAULT_RANGE,
+      });
+    });
+  });
+  describe('serializeStateToUrlParam', () => {
+    it('returns url parameter value for a state object', () => {
+      const state = {
+        ...DEFAULT_EXPLORE_STATE,
+        datasourceName: 'foo',
+        range: {
+          from: 'now - 5h',
+          to: 'now',
+        },
+        queries: [
+          {
+            query: 'metric{test="a/b"}',
+          },
+          {
+            query: 'super{foo="x/z"}',
+          },
+        ],
+      };
+      expect(serializeStateToUrlParam(state)).toBe(
+        '{"datasource":"foo","queries":[{"query":"metric{test=\\"a/b\\"}"},' +
+          '{"query":"super{foo=\\"x/z\\"}"}],"range":{"from":"now - 5h","to":"now"}}'
+      );
+    });
+  });
+  describe('interplay', () => {
+    it('can parse the serialized state into the original state', () => {
+      const state = {
+        ...DEFAULT_EXPLORE_STATE,
+        datasourceName: 'foo',
+        range: {
+          from: 'now - 5h',
+          to: 'now',
+        },
+        queries: [
+          {
+            query: 'metric{test="a/b"}',
+          },
+          {
+            query: 'super{foo="x/z"}',
+          },
+        ],
+      };
+      const serialized = serializeStateToUrlParam(state);
+      const parsed = parseUrlState(serialized);
+
+      // Account for datasource vs datasourceName
+      const { datasource, ...rest } = parsed;
+      const sameState = {
+        ...rest,
+        datasource: DEFAULT_EXPLORE_STATE.datasource,
+        datasourceName: datasource,
+      };
+
+      expect(state).toMatchObject(sameState);
+    });
+  });
+});