feat(core): Default and custom 'main' module block resolution.

Author: amiller-gh

packages/@css-blocks/core/src/importing/NodeJsImporter.ts

@@ -1,13 +1,15 @@
 import { ObjectDictionary } from "@opticss/util";
 
-import { existsSync, readFile } from "fs-extra";
+import { existsSync, readFile, readFileSync } from "fs-extra";
 import * as path from "path";
 
 import { Syntax } from "../BlockParser";
 import { ResolvedConfiguration } from "../configuration";
 
 import { FileIdentifier, ImportedFile, Importer } from "./Importer";
 
+const DEFAULT_MAIN = "blocks/index.block.css";
+
 /**
  * An Alias maps the starting segment of a relative import path to a
  * corresponding absolute path to attempt to resolve against.
@@ -53,11 +55,19 @@ export class NodeJsImporter implements Importer {
       return path.resolve(alias.path, importPath.substring(alias.alias.length + 1));
     }
 
-    // If no alias found, test for a node_module resolution.
+    // If no alias found, test for a node_module resolution as a file path.
     try {
       return require.resolve(importPath, { paths: [config.rootDir] });
     } catch (err) {}
 
+    // If no alias found, test for a node_module resolution as a package name.
+    try {
+      const pjsonPath = require.resolve(path.join(importPath, "package.json"), { paths: [config.rootDir] });
+      const pjson = JSON.parse(readFileSync(pjsonPath, "utf-8"));
+      const main: string | undefined = pjson["css-blocks"] && pjson["css-blocks"].main;
+      return path.resolve(pjsonPath, "..", main || DEFAULT_MAIN);
+    } catch (err) { console.log(err); }
+
     // If no backup alias or node_module fount, return the previously calculated
     // absolute path where we expect it should be.
     return resolvedPath;

packages/@css-blocks/core/test/importing-test.ts

@@ -95,7 +95,7 @@ testFSImporter("FilesystemImporter", defaultImporter);
 testFSImporter("Default PathAliasImporter", new NodeJsImporter({}));
 testFSImporter("Configured PathAliasImporter", new NodeJsImporter({alias: ALIAS_FIXTURES}));
 
-describe("Node Module Importer", () => {
+describe("Node Module Importer – Fully Qualified Paths", () => {
   before(function(this: IHookCallbackContext) {
     this.importer = new NodeJsImporter();
     this.config = getConfiguration(NODE_MODULE_FIXTURES);
@@ -123,6 +123,41 @@ describe("Node Module Importer", () => {
   });
 });
 
+describe("Node Module Importer – Package Names", () => {
+  before(function(this: IHookCallbackContext) {
+    this.importer = new NodeJsImporter();
+    this.config = getConfiguration(NODE_MODULE_FIXTURES);
+  });
+  it("handles un-scoped packages default package export", function() {
+    let packageName = "package";
+    let ident = this.importer.identifier(null, packageName, this.config);
+    let resolvedFilename = this.importer.filesystemPath(ident, this.config);
+    assert.equal(ident, path.join(NODE_MODULE_FIXTURES, "node_modules", packageName, "blocks", "index.block.css"));
+    assert.equal(resolvedFilename, path.join(NODE_MODULE_FIXTURES, "node_modules", packageName, "blocks", "index.block.css"));
+  });
+  it("handles scoped packages default package export", function() {
+    let packageName = "@scoped/package";
+    let ident = this.importer.identifier(null, packageName, this.config);
+    let resolvedFilename = this.importer.filesystemPath(ident, this.config);
+    assert.equal(ident, path.join(NODE_MODULE_FIXTURES, "node_modules", packageName, "blocks", "index.block.css"));
+    assert.equal(resolvedFilename, path.join(NODE_MODULE_FIXTURES, "node_modules", packageName, "blocks", "index.block.css"));
+  });
+  it("handles packages with a custom main block export", function() {
+    let packageName = "@scoped/custom-main";
+    let ident = this.importer.identifier(null, packageName, this.config);
+    let resolvedFilename = this.importer.filesystemPath(ident, this.config);
+    assert.equal(ident, path.join(NODE_MODULE_FIXTURES, "node_modules", packageName, "blocks", "custom.block.css"));
+    assert.equal(resolvedFilename, path.join(NODE_MODULE_FIXTURES, "node_modules", packageName, "blocks", "custom.block.css"));
+  });
+  it("gracefully degrades back to relative lookup for undiscoverable modules. Is never found without extension.", function() {
+    let packageName = "@scoped/non-existent";
+    let ident = this.importer.identifier(null, packageName, this.config);
+    let resolvedFilename = this.importer.filesystemPath(ident, this.config);
+    assert.equal(ident, path.join(NODE_MODULE_FIXTURES, packageName));
+    assert.equal(resolvedFilename, null);
+  });
+});
+
 describe("PathAliasImporter", () => {
   before(function(this: IHookCallbackContext) {
     let aliases = {