Add user-specified conditions to ESM resolution

lib/trace.js

@@ -151,7 +151,9 @@ const _recurseDeps = async ({
   bailOnMissing = true,
   includeSourceMaps = false,
   _extraImports,
-  _tracedDepPaths
+  _tracedDepPaths,
+  userConditions,
+  replaceConditions
 }) => {
   // Start **only** with depPaths.
   let dependencies = Array.from(depPaths);
@@ -181,7 +183,9 @@ const _recurseDeps = async ({
         bailOnMissing,
         includeSourceMaps,
         _extraImports,
-        _tracedDepPaths
+        _tracedDepPaths,
+        userConditions,
+        replaceConditions
       });
 
       // Aggregate.
@@ -208,6 +212,8 @@ const _resolveDep = async ({
   addMisses,
   allowMissing,
   bailOnMissing,
+  userConditions,
+  replaceConditions,
   addRootPackagePaths = false
 }) => {
   // Capture all package.json files encountered in node resolution.
@@ -298,7 +304,9 @@ const _resolveDep = async ({
           }
         });
 
-        CONDITIONS.forEach((cond) => {
+        const conditions = replaceConditions ? userConditions : CONDITIONS.concat(userConditions);
+
+        conditions.forEach((cond) => {
           let resolveOpts;
           if (Array.isArray(cond)) {
             resolveOpts = cond[1];
@@ -452,6 +460,8 @@ const _resolveDep = async ({
  * @param {Object}        opts.extraImports       map files to additional imports to trace
  * @param {Object}        opts._extraImports      (internal) normalized map
  * @param {Set}           opts._tracedDepPaths    (internal) tracked dependencies
+ * @param {Array<string>} opts.userConditions     list of conditional exports https://nodejs.org/api/packages.html#packages_conditional_exports
+ * @param {boolean}       opts.replaceConditions  flag to replace conditions with userConditions
  * @returns {Promise<Object>}                     dependencies and other information
  */
 // eslint-disable-next-line max-statements,complexity
@@ -463,7 +473,9 @@ const traceFile = async ({
   includeSourceMaps = false,
   extraImports = {},
   _extraImports,
-  _tracedDepPaths = new Set()
+  _tracedDepPaths = new Set(),
+  userConditions = [],
+  replaceConditions = false
 } = {}) => {
   if (!srcPath) {
     throw new Error("Empty source file path");
@@ -553,7 +565,9 @@ const traceFile = async ({
       extraDepKeys,
       addMisses,
       allowMissing,
-      bailOnMissing
+      bailOnMissing,
+      userConditions,
+      replaceConditions
     })))
     // Post-resolution processing.
     .then((allPaths) => allPaths
@@ -614,6 +628,8 @@ const traceFile = async ({
  * @param {Object}        opts.extraImports       map files to additional imports to trace
  * @param {Object}        opts._extraImports      (internal) normalized map
  * @param {Set}           opts._tracedDepPaths    (internal) tracked dependencies
+ * @param {Array<string>} opts.userConditions     list of conditional exports https://nodejs.org/api/packages.html#packages_conditional_exports
+ * @param {boolean}       opts.replaceConditions  flag to replace conditions with userConditions
  * @returns {Promise<Object>}                     dependencies and other information
  */
 const traceFiles = async ({
@@ -624,7 +640,9 @@ const traceFiles = async ({
   includeSourceMaps = false,
   extraImports = {},
   _extraImports,
-  _tracedDepPaths = new Set()
+  _tracedDepPaths = new Set(),
+  userConditions = [],
+  replaceConditions = false
 } = {}) => {
   _extraImports = _extraImports || normalizeExtraImports(extraImports);
 
@@ -636,7 +654,9 @@ const traceFiles = async ({
     bailOnMissing,
     includeSourceMaps,
     _extraImports,
-    _tracedDepPaths
+    _tracedDepPaths,
+    userConditions,
+    replaceConditions
   });
 
   // Make unique and return.

test/lib/trace.spec.js

@@ -2793,5 +2793,110 @@ describe("lib/trace", () => {
         }
       });
     });
+
+    it("Replace conditions with supplied userConditions when tracing files", async () => {
+      mock({
+        "hi.js": `
+          const core = require("trace/core");
+        `,
+        node_modules: {
+          trace: {
+            "package.json": stringify({
+              name: "trace",
+              main: "index.cjs",
+              exports: {
+                ".": {
+                  require: "index.cjs"
+                },
+                "./core": {
+                  lite: {
+                    node: "./core-lite.cjs"
+                  },
+                  require: "./core.cjs"
+                }
+              }
+            }),
+            "index.cjs": `
+              const hello = () => {};
+              module.exports = hello;
+            `,
+            "core.cjs": `
+              const core = () => {};
+
+              module.exports = core;
+            `,
+            "core-lite.cjs": `
+              const coreLight = () => {};
+
+              module.exports = coreLight;
+            `
+          }
+        }
+      });
+
+      const { dependencies } = await traceFiles({
+        srcPaths: ["hi.js"],
+        userConditions: ["lite"],
+        replaceConditions: true
+      });
+
+      expect(dependencies).to.eql(fullPaths([
+        "node_modules/trace/core-lite.cjs",
+        "node_modules/trace/package.json"
+      ]));
+    });
+
+    it("Append supplied userConditions to conditions when tracing files", async () => {
+      mock({
+        "hi.js": `
+          const core = require("trace/core");
+        `,
+        node_modules: {
+          trace: {
+            "package.json": stringify({
+              name: "trace",
+              main: "index.cjs",
+              exports: {
+                ".": {
+                  require: "index.cjs"
+                },
+                "./core": {
+                  lite: {
+                    node: "./core-lite.cjs"
+                  },
+                  require: "./core.cjs"
+                }
+              }
+            }),
+            "index.cjs": `
+              const hello = () => {};
+              module.exports = hello;
+            `,
+            "core.cjs": `
+              const core = () => {};
+
+              module.exports = core;
+            `,
+            "core-lite.cjs": `
+              const coreLight = () => {};
+
+              module.exports = coreLight;
+            `
+          }
+        }
+      });
+
+      const { dependencies } = await traceFiles({
+        srcPaths: ["hi.js"],
+        userConditions: ["lite"],
+        replaceConditions: false
+      });
+
+      expect(dependencies).to.eql(fullPaths([
+        "node_modules/trace/core-lite.cjs",
+        "node_modules/trace/core.cjs",
+        "node_modules/trace/package.json"
+      ]));
+    });
   });
 });