[Lens] Do not reset formatting when switching between custom ranges and auto histogram

x-pack/plugins/lens/public/indexpattern_datasource/operations/definitions/ranges/ranges.test.tsx

@@ -744,6 +744,36 @@ describe('ranges', () => {
           /^Bytes format:/
         );
       });
+
+      it('should not reset formatters when switching between custom ranges and auto histogram', () => {
+        const setStateSpy = jest.fn();
+        // now set a format on the range operation
+        (state.layers.first.columns.col1 as RangeIndexPatternColumn).params.format = {
+          id: 'custom',
+          params: { decimals: 3 },
+        };
+
+        const instance = mount(
+          <InlineOptions
+            {...defaultOptions}
+            state={state}
+            setState={setStateSpy}
+            columnId="col1"
+            currentColumn={state.layers.first.columns.col1 as RangeIndexPatternColumn}
+            layerId="first"
+          />
+        );
+
+        // This series of act closures are made to make it work properly the update flush
+        act(() => {
+          instance.find(EuiLink).first().prop('onClick')!({} as ReactMouseEvent);
+        });
+
+        expect(setStateSpy.mock.calls[1][0].layers.first.columns.col1.params.format).toEqual({
+          id: 'custom',
+          params: { decimals: 3 },
+        });
+      });
     });
   });
 });

x-pack/plugins/lens/public/indexpattern_datasource/operations/definitions/ranges/ranges.tsx

@@ -225,7 +225,7 @@ export const rangeOperation: OperationDefinition<RangeIndexPatternColumn, 'field
               type: newMode,
               ranges: [{ from: 0, to: DEFAULT_INTERVAL, label: '' }],
               maxBars: maxBarsDefaultValue,
-              format: undefined,
+              format: currentColumn.params.format,
               parentFormat,
             },
           },