Revert Relax material ui version dependency

Refs marmelab#3102

docs/FAQ.md

@@ -11,6 +11,7 @@ title: "FAQ"
 - [How can I customize the UI depending on the user permissions?](#how-can-i-customize-the-ui-depending-on-the-user-permissions)
 - [How can I customize forms depending on its inputs values?](#how-can-i-customize-forms-depending-on-its-inputs-values)
 - [My Resource is defined but not displayed on the Menu](#my-resource-is-defined-but-not-displayed-on-the-menu)
+- [Why React Admin Doesn't Support The Latest Version Of Material-UI?](#why-react-admin-doesnt-support-the-latest-version-of-material-ui)
 
 ## Can I have custom identifiers/primary keys for my resources?
 
@@ -132,3 +133,13 @@ In order to have a specific resource without `list` prop listed on the menu, you
     </div>
 );
 ```
+
+## Why Doesn't React Admin Support The Latest Version Of Material-UI?
+
+React Admin users and third-party libraries maintainers might have noticed that the default UI template `ra-ui-materialui` [has `@material-ui/core@^1.4.0` as dependency](https://github.com/marmelab/react-admin/blob/ae45a2509b391a6ea81cdf9c248ff9d28364b6e1/packages/ra-ui-materialui/package.json#L44) even though the latest version of Material UI is already 3.x.
+
+We chose not to upgrade to Material UI v3 when it was released because the MUI team was already hard at work preparing the next major version ([which includes major breaking changes](https://github.com/mui-org/material-ui/issues/13663)). In fact, material-ui published a release schedule for one major version every 6 months. This means that developers using material-ui have to upgrade their codebase every six months to get the latest updates. On the other hand, react-admin plans to release a major version once every year, minimizing the upgrade work for developers. This gain in stability is a tradeoff - react-admin users can't use the latest version of material-ui for about half a year.
+
+Feel free to discuss this policy in [issue #2399](https://github.com/marmelab/react-admin/issues/2399).
+
+If you are a maintainer of a third-party library based on React Admin, your library has to add material-ui v1.x as a peer dependency.

examples/demo/package.json

@@ -3,8 +3,8 @@
     "version": "0.1.0",
     "private": true,
     "dependencies": {
-        "@material-ui/core": "~3.9.3",
-        "@material-ui/icons": "~3.0.2",
+        "@material-ui/core": "~1.5.1",
+        "@material-ui/icons": "~1.1.1",
         "data-generator-retail": "^2.7.0",
         "fakerest": "~2.1.0",
         "fetch-mock": "~6.3.0",

examples/simple/package.json

@@ -37,8 +37,8 @@
         "webpack-dev-server": "~3.1.11"
     },
     "dependencies": {
-        "@material-ui/core": "~3.9.3",
-        "@material-ui/icons": "~3.0.2",
+        "@material-ui/core": "~1.5.1",
+        "@material-ui/icons": "~1.1.1",
         "@babel/polyfill": "^7.0.0",
         "ra-data-fakerest": "^2.0.0",
         "ra-input-rich-text": "^2.0.0",

examples/tutorial/package.json

@@ -3,7 +3,7 @@
     "version": "0.1.0",
     "private": true,
     "dependencies": {
-        "@material-ui/core": "~3.9.3",
+        "@material-ui/core": "~1.5.1",
         "ra-data-json-server": "^2.0.0",
         "react": "~16.3.1",
         "react-admin": "^2.0.0",

packages/ra-ui-materialui/package.json

@@ -26,8 +26,8 @@
         "watch": "rimraf ./lib && tsc --watch"
     },
     "devDependencies": {
-        "@material-ui/core": "~3.9.3",
-        "@material-ui/icons": "~3.0.2",
+        "@material-ui/core": "~1.5.1",
+        "@material-ui/icons": "~1.1.1",
         "cross-env": "^5.2.0",
         "enzyme": "~3.7.0",
         "enzyme-adapter-react-16": "~1.6.0",
@@ -43,8 +43,8 @@
         "react-dom": "^16.3.0"
     },
     "dependencies": {
-        "@material-ui/core": "^1.4.0 || ^3.0.0",
-        "@material-ui/icons": "^1.0.0 || ^3.0.0",
+        "@material-ui/core": "^1.4.0",
+        "@material-ui/icons": "^1.0.0",
         "autosuggest-highlight": "^3.1.1",
         "classnames": "~2.2.5",
         "inflection": "~1.12.0",

packages/ra-ui-materialui/src/field/BooleanField.spec.js

@@ -6,15 +6,17 @@ import { render, cleanup } from 'react-testing-library';
 describe('<BooleanField />', () => {
     afterEach(cleanup);
     it('should display tick and truthy text if value is true', () => {
-        const { queryByText, getByRole } = render(
+        const { queryByText } = render(
             <BooleanField
                 record={{ published: true }}
                 source="published"
                 resource="posts"
             />
         );
         expect(queryByText('ra.boolean.true')).not.toBeNull();
-        expect(getByRole('presentation').dataset.testid).toBe('true');
+        expect(queryByText('ra.boolean.true').nextSibling.dataset.testid).toBe(
+            'true'
+        );
         expect(queryByText('ra.boolean.false')).toBeNull();
     });
 
@@ -32,16 +34,18 @@ describe('<BooleanField />', () => {
     });
 
     it('should display cross and falsy text if value is false', () => {
-        const { queryByText, getByRole } = render(
+        const { queryByText } = render(
             <BooleanField
                 record={{ published: false }}
                 source="published"
                 resource="posts"
             />
         );
         expect(queryByText('ra.boolean.true')).toBeNull();
-        expect(getByRole('presentation').dataset.testid).toBe('false');
         expect(queryByText('ra.boolean.false')).not.toBeNull();
+        expect(queryByText('ra.boolean.false').nextSibling.dataset.testid).toBe(
+            'false'
+        );
     });
 
     it('should use valueLabelFalse for custom falsy text', () => {