Parsing: Enforce block naming requirements consistently

blocks/api/post.pegjs

@@ -283,36 +283,25 @@ Block_Name
   / Core_Block_Name
 
 Namespaced_Block_Name
-  = $(ASCII_Letter ASCII_AlphaNumeric* "/" ASCII_Letter ASCII_AlphaNumeric*)
+  = $( Block_Name_Part "/" Block_Name_Part )
 
 Core_Block_Name
-  = type:$(ASCII_Letter ASCII_AlphaNumeric*)
+  = type:$( Block_Name_Part )
   {
     /** <?php return "core/$type"; ?> **/
     return 'core/' + type;
   }
 
+Block_Name_Part
+  = $( [a-z][a-z0-9_-]* )
+
 Block_Attributes
   = attrs:$("{" (!("}" WS+ """/"? "-->") .)* "}")
   {
     /** <?php return json_decode( $attrs, true ); ?> **/
     return maybeJSON( attrs );
   }
 
-ASCII_AlphaNumeric
-  = ASCII_Letter
-  / ASCII_Digit
-  / Special_Chars
-
-ASCII_Letter
-  = [a-zA-Z]
-
-ASCII_Digit
-  = [0-9]
-
-Special_Chars
-  = [\-\_]
-
 WS
   = [ \t\r\n]
 

blocks/api/registration.js

@@ -55,15 +55,9 @@ export function registerBlockType( name, settings ) {
 		);
 		return;
 	}
-	if ( /[A-Z]+/.test( name ) ) {
+	if ( ! /^[a-z][a-z0-9-]*\/[a-z][a-z0-9-]*$/.test( name ) ) {
 		console.error(
-			'Block names must not contain uppercase characters.'
-		);
-		return;
-	}
-	if ( ! /^[a-z0-9-]+\/[a-z0-9-]+$/.test( name ) ) {
-		console.error(
-			'Block names must contain a namespace prefix. Example: my-plugin/my-custom-block'
+			'Block names must contain a namespace prefix, include only lowercase alphanumeric characters or dashes, and start with a letter. Example: my-plugin/my-custom-block'
 		);
 		return;
 	}

blocks/api/test/registration.js

@@ -48,25 +48,31 @@ describe( 'blocks', () => {
 
 		it( 'should reject blocks without a namespace', () => {
 			const block = registerBlockType( 'doing-it-wrong' );
-			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix. Example: my-plugin/my-custom-block' );
+			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix, include only lowercase alphanumeric characters or dashes, and start with a letter. Example: my-plugin/my-custom-block' );
 			expect( block ).toBeUndefined();
 		} );
 
 		it( 'should reject blocks with too many namespaces', () => {
 			const block = registerBlockType( 'doing/it/wrong' );
-			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix. Example: my-plugin/my-custom-block' );
+			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix, include only lowercase alphanumeric characters or dashes, and start with a letter. Example: my-plugin/my-custom-block' );
 			expect( block ).toBeUndefined();
 		} );
 
 		it( 'should reject blocks with invalid characters', () => {
 			const block = registerBlockType( 'still/_doing_it_wrong' );
-			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix. Example: my-plugin/my-custom-block' );
+			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix, include only lowercase alphanumeric characters or dashes, and start with a letter. Example: my-plugin/my-custom-block' );
 			expect( block ).toBeUndefined();
 		} );
 
 		it( 'should reject blocks with uppercase characters', () => {
 			const block = registerBlockType( 'Core/Paragraph' );
-			expect( console.error ).toHaveBeenCalledWith( 'Block names must not contain uppercase characters.' );
+			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix, include only lowercase alphanumeric characters or dashes, and start with a letter. Example: my-plugin/my-custom-block' );
+			expect( block ).toBeUndefined();
+		} );
+
+		it( 'should reject blocks not starting with a letter', () => {
+			const block = registerBlockType( 'my-plugin/4-fancy-block', defaultBlockSettings );
+			expect( console.error ).toHaveBeenCalledWith( 'Block names must contain a namespace prefix, include only lowercase alphanumeric characters or dashes, and start with a letter. Example: my-plugin/my-custom-block' );
 			expect( block ).toBeUndefined();
 		} );
 

blocks/test/fixtures/core__4-invalid-starting-letter.html

@@ -0,0 +1 @@
+<!-- wp:core/4-invalid /-->

blocks/test/fixtures/core__4-invalid-starting-letter.json

@@ -0,0 +1,11 @@
+[
+    {
+        "uid": "_uid_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<!-- wp:core/4-invalid /-->"
+        },
+        "originalContent": "<!-- wp:core/4-invalid /-->"
+    }
+]

blocks/test/fixtures/core__4-invalid-starting-letter.parsed.json

@@ -0,0 +1,6 @@
+[
+    {
+        "attrs": {},
+        "innerHTML": "<!-- wp:core/4-invalid /-->\n"
+    }
+]

blocks/test/fixtures/core__4-invalid-starting-letter.serialized.html

@@ -0,0 +1 @@
+<!-- wp:core/4-invalid /-->

blocks/test/fixtures/core__invalid-Capitals.html

@@ -0,0 +1 @@
+<!-- wp:core/invalid-Capitals /-->

blocks/test/fixtures/core__invalid-Capitals.json

@@ -0,0 +1,11 @@
+[
+    {
+        "uid": "_uid_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<!-- wp:core/invalid-Capitals /-->"
+        },
+        "originalContent": "<!-- wp:core/invalid-Capitals /-->"
+    }
+]

blocks/test/fixtures/core__invalid-Capitals.parsed.json

@@ -0,0 +1,6 @@
+[
+    {
+        "attrs": {},
+        "innerHTML": "<!-- wp:core/invalid-Capitals /-->\n"
+    }
+]

blocks/test/fixtures/core__invalid-Capitals.serialized.html

@@ -0,0 +1 @@
+<!-- wp:core/invalid-Capitals /-->

blocks/test/fixtures/core__invalid-special.html

@@ -0,0 +1 @@
+<!-- wp:core/invalid-$special /-->

blocks/test/fixtures/core__invalid-special.json

@@ -0,0 +1,11 @@
+[
+    {
+        "uid": "_uid_0",
+        "name": "core/freeform",
+        "isValid": true,
+        "attributes": {
+            "content": "<!-- wp:core/invalid-$special /-->"
+        },
+        "originalContent": "<!-- wp:core/invalid-$special /-->"
+    }
+]

blocks/test/fixtures/core__invalid-special.parsed.json

@@ -0,0 +1,6 @@
+[
+    {
+        "attrs": {},
+        "innerHTML": "<!-- wp:core/invalid-$special /-->\n"
+    }
+]

blocks/test/fixtures/core__invalid-special.serialized.html

@@ -0,0 +1 @@
+<!-- wp:core/invalid-$special /-->

docs/block-api.md

@@ -19,7 +19,9 @@ The name for a block is a unique string that identifies a block. Names have to b
 registerBlockType( 'my-plugin/book', {} );
 ```
 
-*Note:* this name is used on the comment delimiters as `<!-- wp:my-plugin/book -->`. Those blocks provided by core don't include a namespace when serialized.
+*Note:* A block name can only contain lowercase alphanumeric characters and dashes, and must begin with a letter.
+
+*Note:* This name is used on the comment delimiters as `<!-- wp:my-plugin/book -->`. Those blocks provided by core don't include a namespace when serialized.
 
 ### Block Configuration