feat: add reactStrictMode option to enable strict mode render (#1241)

* feat: add `reactStrictMode` option and override `getConfig` and `configure` functions from DTL

* feat: update types for overridden `getConfig` and `configure` functions

* test: add tests for checking configure APIs support RTL option and do not degrade

* refactor: use a wrapper option for simplicity

* refactor: use same function for wrapping UI if needed

* feat: enable strict mode render if `reactStrictMode` option is true

* test: add tests for checking strict mode works and can be combine with wrapper

---------

Co-authored-by: Sebastian Silbermann <silbermann.sebastian@gmail.com>

src/__tests__/__snapshots__/render.js.snap

@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`supports fragments 1`] = `
+exports[`render API supports fragments 1`] = `
 <DocumentFragment>
   <div>
     <code>

src/__tests__/config.js

@@ -0,0 +1,66 @@
+import {configure, getConfig} from '../'
+
+describe('configuration API', () => {
+  let originalConfig
+  beforeEach(() => {
+    // Grab the existing configuration so we can restore
+    // it at the end of the test
+    configure(existingConfig => {
+      originalConfig = existingConfig
+      // Don't change the existing config
+      return {}
+    })
+  })
+
+  afterEach(() => {
+    configure(originalConfig)
+  })
+
+  describe('DTL options', () => {
+    test('configure can set by a plain JS object', () => {
+      const testIdAttribute = 'not-data-testid'
+      configure({testIdAttribute})
+
+      expect(getConfig().testIdAttribute).toBe(testIdAttribute)
+    })
+
+    test('configure can set by a function', () => {
+      // setup base option
+      const baseTestIdAttribute = 'data-testid'
+      configure({testIdAttribute: baseTestIdAttribute})
+
+      const modifiedPrefix = 'modified-'
+      configure(existingConfig => ({
+        testIdAttribute: `${modifiedPrefix}${existingConfig.testIdAttribute}`,
+      }))
+
+      expect(getConfig().testIdAttribute).toBe(
+        `${modifiedPrefix}${baseTestIdAttribute}`,
+      )
+    })
+  })
+
+  describe('RTL options', () => {
+    test('configure can set by a plain JS object', () => {
+      configure({reactStrictMode: true})
+
+      expect(getConfig().reactStrictMode).toBe(true)
+    })
+
+    test('configure can set by a function', () => {
+      configure(existingConfig => ({
+        reactStrictMode: !existingConfig.reactStrictMode,
+      }))
+
+      expect(getConfig().reactStrictMode).toBe(true)
+    })
+  })
+
+  test('configure can set DTL and RTL options at once', () => {
+    const testIdAttribute = 'not-data-testid'
+    configure({testIdAttribute, reactStrictMode: true})
+
+    expect(getConfig().testIdAttribute).toBe(testIdAttribute)
+    expect(getConfig().reactStrictMode).toBe(true)
+  })
+})