ref(perf): Add default display tests for landing (#25904)

This will test some of the default display mechanics of landing to ensure we don't regress, in lieu of writing full component tests for each edge case.

Refs VIS-649

tests/js/spec/views/performance/landing/utils.spec.jsx

@@ -0,0 +1,66 @@
+import {initializeOrg} from 'sentry-test/initializeOrg';
+
+import ProjectsStore from 'app/stores/projectsStore';
+import EventView from 'app/utils/discover/eventView';
+import {getCurrentLandingDisplay} from 'app/views/performance/landing/utils';
+
+function initializeData(projects, query) {
+  const organization = TestStubs.Organization({
+    features: [],
+    projects,
+  });
+  const initialData = initializeOrg({
+    organization,
+    router: {
+      location: {
+        query: query || {},
+      },
+    },
+  });
+  const eventView = EventView.fromLocation(initialData.router.location);
+  ProjectsStore.loadInitialData(initialData.organization.projects);
+  return {
+    ...initialData,
+    eventView,
+  };
+}
+
+describe('Utils', function () {
+  describe('getCurrentLandingDisplay()', function () {
+    it('returns all by default', function () {
+      const projects = [TestStubs.Project()];
+      const data = initializeData(projects);
+      expect(getCurrentLandingDisplay(data.router.location, projects).label).toEqual(
+        'All Transactions'
+      );
+    });
+    it('returns specific landing display if query is set', function () {
+      const projects = [TestStubs.Project()];
+      const data = initializeData(projects, {landingDisplay: 'frontend_pageload'});
+      expect(getCurrentLandingDisplay(data.router.location, projects).label).toEqual(
+        'Frontend (Pageload)'
+      );
+    });
+    it('returns frontend display if project matches', function () {
+      const projects = [TestStubs.Project({id: '22', platform: 'javascript-react'})];
+      const data = initializeData(projects, {project: 22});
+      expect(
+        getCurrentLandingDisplay(data.router.location, projects, data.eventView).label
+      ).toEqual('Frontend (Pageload)');
+    });
+    it('returns backend display if project matches', function () {
+      const projects = [TestStubs.Project({id: '22', platform: 'php'})];
+      const data = initializeData(projects, {project: 22});
+      expect(
+        getCurrentLandingDisplay(data.router.location, projects, data.eventView).label
+      ).toEqual('Backend');
+    });
+    it('returns all display if multiple projects', function () {
+      const projects = [TestStubs.Project()];
+      const data = initializeData(projects, {project: [1, 2]});
+      expect(
+        getCurrentLandingDisplay(data.router.location, projects, data.eventView).label
+      ).toEqual('All Transactions');
+    });
+  });
+});