Fix bug in remark-version-alias (#210)

Fixes #209

The plugin fails to process multiple successive `import` statements as
expected in MDX files because it only operates on `MdxjsEsm` nodes with
a single element in the `data.estree.body` array. Multiple successive
`import` statements add elements to `body`.

This change replaces the `@version` alias in multiple successive imports
by replacing each node, then adding the concatenated replaced values of
all imports to the `MdxjsEsm` node's `value`.

Author: ptgott

server/remark-version-alias.test.ts

@@ -39,7 +39,32 @@ title: My page
 description: My page
 ---
 
-import CodeExample from '@site/content/15.x/examples/access-plugin-minimal/config.go'
+import CodeExample from '@site/content/15.x/examples/access-plugin-minimal/config.go';
+
+This is a paragraph.
+`,
+      path: "docs/mypage.mdx",
+    },
+{
+      description: "three import statements in latest-version docs path",
+      input: `---
+title: My page
+description: My page
+---
+
+import CodeExample from "@version/examples/access-plugin-minimal/config.go";
+import MyImage from "@version/myimg.png";
+import Triangle from "@version/triangle.png";
+
+This is a paragraph.`,
+      expected: `---
+title: My page
+description: My page
+---
+
+import CodeExample from '@site/content/15.x/examples/access-plugin-minimal/config.go';
+import MyImage from '@site/content/15.x/myimg.png';
+import Triangle from '@site/content/15.x/triangle.png';
 
 This is a paragraph.
 `,
@@ -60,7 +85,7 @@ title: My page
 description: My page
 ---
 
-import CodeExample from '@site/content/16.x/examples/access-plugin-minimal/config.go'
+import CodeExample from '@site/content/16.x/examples/access-plugin-minimal/config.go';
 
 This is a paragraph.
 `,
@@ -81,7 +106,7 @@ title: My page
 description: My page
 ---
 
-import CodeExample from '!!raw-loader!@site/content/16.x/examples/access-plugin-minimal/config.go'
+import CodeExample from '!!raw-loader!@site/content/16.x/examples/access-plugin-minimal/config.go';
 
 This is a paragraph.
 `,

server/remark-version-alias.ts

@@ -17,36 +17,41 @@ export default function remarkVersionAlias(latestVersion: string): Transformer {
       // Only process import statements that import an identifier from a default
       // export.
       const esm = node as unknown as MdxjsEsm;
-      if (
-        !esm.data ||
-        !esm.data.estree ||
-        esm.data.estree.body.length !== 1 ||
-        esm.data.estree.body[0]["type"] != "ImportDeclaration" ||
-        esm.data.estree.body[0].specifiers.length !== 1 ||
-        esm.data.estree.body[0].specifiers[0].type != "ImportDefaultSpecifier"
-      ) {
+      if (!esm.data || !esm.data.estree) {
         return CONTINUE;
       }
 
       let version: string = latestVersion;
+      let newVal: Array<string> = [];
       const versionedPathParts = vfile.path.match(versionedDocsPattern);
       if (versionedPathParts) {
         version = versionedPathParts[1];
       }
 
-      const decl = esm.data.estree.body[0];
-
-      const newPath = (decl.source.value as string).replace(
-        "@version",
-        `@site/content/${version}`,
-      );
-
-      esm.value = `import ${esm.data.estree.body[0].specifiers[0].local.name} from '${newPath}'`;
-      decl.source = {
-        type: "Literal",
-        value: newPath,
-        raw: `"${newPath}"`,
-      };
+      esm.data.estree.body.forEach((decl) => {
+        if (
+          decl["type"] != "ImportDeclaration" ||
+          decl.specifiers.length !== 1 ||
+          decl.specifiers[0].type != "ImportDefaultSpecifier"
+        ) {
+          return;
+        }
+        const newPath = (decl.source.value as string).replace(
+          "@version",
+          `@site/content/${version}`,
+        );
+        decl.source = {
+          type: "Literal",
+          value: newPath,
+          raw: `"${newPath}"`,
+        };
+
+        newVal.push(
+          `import ${decl.specifiers[0].local.name} from '${newPath}';`,
+        );
+      });
+
+      esm.value = newVal.join("\n");
 
       return SKIP;
     });