Prometheus: Prevents validation of inputs when clicking in them without changing the value (#21059)

Fixes #21056

public/app/plugins/datasource/prometheus/configuration/PromSettings.test.tsx

@@ -1,4 +1,5 @@
-import { getValueFromEventItem } from './PromSettings';
+import { getValueFromEventItem, promSettingsValidationEvents } from './PromSettings';
+import { EventsWithValidation } from '@grafana/ui';
 
 describe('PromSettings', () => {
   describe('getValueFromEventItem', () => {
@@ -25,4 +26,57 @@ describe('PromSettings', () => {
       });
     });
   });
+
+  describe('promSettingsValidationEvents', () => {
+    const validationEvents = promSettingsValidationEvents;
+
+    it('should have one event handlers', () => {
+      expect(Object.keys(validationEvents).length).toEqual(1);
+    });
+
+    it('should have an onBlur handler', () => {
+      expect(validationEvents.hasOwnProperty(EventsWithValidation.onBlur)).toBe(true);
+    });
+
+    it('should have one rule', () => {
+      expect(validationEvents[EventsWithValidation.onBlur].length).toEqual(1);
+    });
+
+    describe('when calling the rule with an empty string', () => {
+      it('then it should return true', () => {
+        expect(validationEvents[EventsWithValidation.onBlur][0].rule('')).toBe(true);
+      });
+    });
+
+    it.each`
+      value    | expected
+      ${'1ms'} | ${true}
+      ${'1M'}  | ${true}
+      ${'1w'}  | ${true}
+      ${'1d'}  | ${true}
+      ${'1h'}  | ${true}
+      ${'1m'}  | ${true}
+      ${'1s'}  | ${true}
+      ${'1y'}  | ${true}
+    `(
+      "when calling the rule with correct formatted value: '$value' then result should be '$expected'",
+      ({ value, expected }) => {
+        expect(validationEvents[EventsWithValidation.onBlur][0].rule(value)).toBe(expected);
+      }
+    );
+
+    it.each`
+      value     | expected
+      ${'1 ms'} | ${false}
+      ${'1x'}   | ${false}
+      ${' '}    | ${false}
+      ${'w'}    | ${false}
+      ${'1.0s'} | ${false}
+    `(
+      "when calling the rule with incorrect formatted value: '$value' then result should be '$expected'",
+      ({ value, expected }) => {
+        expect(validationEvents[EventsWithValidation.onBlur][0].rule(value)).toBe(expected);
+      }
+    );
+  });
 });