linked time: add feature flag for prospective fob (#5983)

We want to show a prospective fob on user hovering the axis. This PR
creates a feature flag to hide it until it's ready.

Co-authored-by: Riley Jones <[email protected]>

Author: japie1235813

tensorboard/webapp/feature_flag/store/feature_flag_metadata.ts

@@ -116,6 +116,11 @@ export const FeatureFlagMetadataMap: FeatureFlagMetadataMapType<FeatureFlags> =
       queryParamOverride: 'allowRangeSelection',
       parseValue: parseBoolean,
     },
+    enabledProspectiveFob: {
+      defaultValue: false,
+      queryParamOverride: 'enableProspectiveFob',
+      parseValue: parseBoolean,
+    },
   };
 
 /**

tensorboard/webapp/feature_flag/store/feature_flag_selectors.ts

@@ -163,3 +163,10 @@ export const getAllowRangeSelection = createSelector(
     return flags.allowRangeSelection;
   }
 );
+
+export const getIsLinkedTimeProspectiveFobEnabled = createSelector(
+  getFeatureFlags,
+  (flags: FeatureFlags): boolean => {
+    return flags.enabledProspectiveFob;
+  }
+);

tensorboard/webapp/feature_flag/store/feature_flag_selectors_test.ts

@@ -415,4 +415,33 @@ describe('feature_flag_selectors', () => {
       expect(selectors.getIsDataTableEnabled(state)).toEqual(true);
     });
   });
+
+  describe('#getIsLinkedTimeProspectiveFobEnabled', () => {
+    it('returns the proper value', () => {
+      let state = buildState(
+        buildFeatureFlagState({
+          defaultFlags: buildFeatureFlag({
+            enabledProspectiveFob: false,
+          }),
+        })
+      );
+      expect(selectors.getIsLinkedTimeProspectiveFobEnabled(state)).toEqual(
+        false
+      );
+
+      state = buildState(
+        buildFeatureFlagState({
+          defaultFlags: buildFeatureFlag({
+            enabledProspectiveFob: false,
+          }),
+          flagOverrides: {
+            enabledProspectiveFob: true,
+          },
+        })
+      );
+      expect(selectors.getIsLinkedTimeProspectiveFobEnabled(state)).toEqual(
+        true
+      );
+    });
+  });
 });

tensorboard/webapp/feature_flag/types.ts

@@ -48,4 +48,6 @@ export interface FeatureFlags {
   enableShowFlags: boolean;
   // Adds check box in settings which allows users to enter step selection range.
   allowRangeSelection: boolean;
+  // In Linked Time, if enabled, show a prospective fob user to turn on the feature or select a step.
+  enabledProspectiveFob: boolean;
 }