add mark delimiter to plain text splitter

fixes #668

Author: quantizor

.changeset/pretty-humans-hunt.md

@@ -0,0 +1,5 @@
+---
+'markdown-to-jsx': patch
+---
+
+Fix consecutive marked text.

index.compiler.spec.tsx

@@ -357,6 +357,21 @@ describe('inline textual elements', () => {
     `)
   })
 
+  it('should handle consecutive marked text', () => {
+    render(compiler('==Hello== ==World=='))
+
+    expect(root.innerHTML).toMatchInlineSnapshot(`
+      <span>
+        <mark>
+          Hello
+        </mark>
+        <mark>
+          World
+        </mark>
+      </span>
+    `)
+  })
+
   it('should handle marked text containing other syntax with an equal sign', () => {
     render(compiler('==Foo `==bar` baz.=='))
 

index.tsx

@@ -326,7 +326,7 @@ const TEXT_UNESCAPE_R = /\\([^0-9A-Za-z\s])/g
  * Always take the first character, then eagerly take text until a double space
  * (potential line break) or some markdown-like punctuation is reached.
  */
-const TEXT_PLAIN_R = /^([\s\S](?:(?!  |[0-9]\.)[^*_~\-\n<`\\\[!])*)/
+const TEXT_PLAIN_R = /^([\s\S](?:(?!  |[0-9]\.)[^=*_~\-\n<`\\\[!])*)/
 
 const TRIM_STARTING_NEWLINES = /^\n+/