Implement rule MD046/code-block-style from Ruby version.

lib/md046.js

@@ -0,0 +1,32 @@
+// @ts-check
+
+"use strict";
+
+const { addErrorDetailIf } = require("../helpers");
+
+const tokenTypeToStyle = {
+  "fence": "fenced",
+  "code_block": "indented"
+};
+
+module.exports = {
+  "names": [ "MD046", "code-block-style" ],
+  "description": "Code block style",
+  "tags": [ "code" ],
+  "function": function MD046(params, onError) {
+    let expectedStyle = params.config.style || "consistent";
+    params.tokens
+      .filter((token) => token.type === "code_block" || token.type === "fence")
+      .forEach((token) => {
+        const { lineNumber, type } = token;
+        if (expectedStyle === "consistent") {
+          expectedStyle = tokenTypeToStyle[type];
+        }
+        addErrorDetailIf(
+          onError,
+          lineNumber,
+          expectedStyle,
+          tokenTypeToStyle[type]);
+      });
+  }
+};