import CssBaseline from "@material-ui/core/CssBaseline";
import MuiThemeProvider from "@material-ui/core/styles/MuiThemeProvider";
import * as React from "react";

import { Provider as DateProvider } from "../components/DateFormatter/DateContext";
import { FormProvider } from "../components/Form";
import { MessageManager } from "../components/messages";
import { TimezoneProvider } from "../components/Timezone";
import theme from "../theme";

export const Decorator = storyFn => (
  <FormProvider>
    <DateProvider value={+new Date("2018-08-07T14:30:44+00:00")}>
      <TimezoneProvider value="America/New_York">
        <MuiThemeProvider theme={theme}>
          <CssBaseline />
          <MessageManager>
            <div>{storyFn()}</div>
          </MessageManager>
        </MuiThemeProvider>
      </TimezoneProvider>
    </DateProvider>
  </FormProvider>
);
export default Decorator;

import CssBaseline from "@material-ui/core/CssBaseline";
import MuiThemeProvider from "@material-ui/core/styles/MuiThemeProvider";
import * as React from "react";

import { Provider as DateProvider } from "../components/DateFormatter/DateContext";
import { MessageManager } from "../components/messages";
import { TimezoneProvider } from "../components/Timezone";
import theme from "../theme";

export const Decorator = storyFn => (
  <DateProvider value={+new Date("2018-08-07T14:30:44+00:00")}>
    <TimezoneProvider value="America/New_York">
      <MuiThemeProvider theme={theme}>
        <CssBaseline />
        <MessageManager>
          <div>{storyFn()}</div>
        </MessageManager>
      </MuiThemeProvider>
    </TimezoneProvider>
  </DateProvider>
);
export default Decorator;

--- 
+++ 
@@ -3,20 +3,23 @@
 import * as React from "react";
 
 import { Provider as DateProvider } from "../components/DateFormatter/DateContext";
+import { FormProvider } from "../components/Form";
 import { MessageManager } from "../components/messages";
 import { TimezoneProvider } from "../components/Timezone";
 import theme from "../theme";
 
 export const Decorator = storyFn => (
-  <DateProvider value={+new Date("2018-08-07T14:30:44+00:00")}>
-    <TimezoneProvider value="America/New_York">
-      <MuiThemeProvider theme={theme}>
-        <CssBaseline />
-        <MessageManager>
-          <div>{storyFn()}</div>
-        </MessageManager>
-      </MuiThemeProvider>
-    </TimezoneProvider>
-  </DateProvider>
+  <FormProvider>
+    <DateProvider value={+new Date("2018-08-07T14:30:44+00:00")}>
+      <TimezoneProvider value="America/New_York">
+        <MuiThemeProvider theme={theme}>
+          <CssBaseline />
+          <MessageManager>
+            <div>{storyFn()}</div>
+          </MessageManager>
+        </MuiThemeProvider>
+      </TimezoneProvider>
+    </DateProvider>
+  </FormProvider>
 );
 export default Decorator;
Add form provider to decorator
