Support fallback syntax in .npmrc file

common/changes/@microsoft/rush/feature-support_fallback_syntax_in_npmrc_2024-12-04-13-22.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Support fallback syntax in .npmrc file",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}

libraries/rush-lib/src/utilities/npmrcUtilities.ts

@@ -32,17 +32,33 @@ function _trimNpmrcFile(options: {
   if (combinedNpmrcFromCache !== undefined) {
     return combinedNpmrcFromCache;
   }
+
   let npmrcFileLines: string[] = [];
   if (linesToPrepend) {
     npmrcFileLines.push(...linesToPrepend);
   }
+
   if (fs.existsSync(sourceNpmrcPath)) {
     npmrcFileLines.push(...fs.readFileSync(sourceNpmrcPath).toString().split('\n'));
   }
+
   if (linesToAppend) {
     npmrcFileLines.push(...linesToAppend);
   }
+
   npmrcFileLines = npmrcFileLines.map((line) => (line || '').trim());
+
+  const resultLines: string[] = trimNpmrcFileLines(npmrcFileLines, process.env);
+
+  const combinedNpmrc: string = resultLines.join('\n');
+
+  //save the cache
+  _combinedNpmrcMap.set(sourceNpmrcPath, combinedNpmrc);
+
+  return combinedNpmrc;
+}
+
+export function trimNpmrcFileLines(npmrcFileLines: string[], env: NodeJS.ProcessEnv): string[] {
   const resultLines: string[] = [];
 
   // This finds environment variable tokens that look like "${VAR_NAME}"
@@ -66,11 +82,30 @@ function _trimNpmrcFile(options: {
       const environmentVariables: string[] | null = line.match(expansionRegExp);
       if (environmentVariables) {
         for (const token of environmentVariables) {
-          // Remove the leading "${" and the trailing "}" from the token
-          const environmentVariableName: string = token.substring(2, token.length - 1);
-
-          // Is the environment variable defined?
-          if (!process.env[environmentVariableName]) {
+          /**
+           * Remove the leading "${" and the trailing "}" from the token
+           *
+           * ${nameString}                  -> nameString
+           * ${nameString-fallbackString}   -> name-fallbackString
+           * ${nameString:-fallbackString}  -> name:-fallbackString
+           */
+          const nameWithFallback: string = token.substring(2, token.length - 1);
+
+          /**
+           * Get the environment variable name and fallback value.
+           *
+           *                                name          fallback
+           * nameString                 ->  nameString    undefined
+           * nameString-fallbackString  ->  nameString    fallbackString
+           * nameString:-fallbackString ->  nameString    fallbackString
+           */
+          const matched: string[] | null = nameWithFallback.match(/^([^:-]+)(?:\:?-(.+))?$/);
+          // matched: [originStr, variableName, fallback]
+          const environmentVariableName: string = matched?.[1] ?? nameWithFallback;
+          const fallback: string | undefined = matched?.[2];
+
+          // Is the environment variable and fallback value defined.
+          if (!env[environmentVariableName] && !fallback) {
             // No, so trim this line
             lineShouldBeTrimmed = true;
             break;
@@ -88,12 +123,7 @@ function _trimNpmrcFile(options: {
     }
   }
 
-  const combinedNpmrc: string = resultLines.join('\n');
-
-  //save the cache
-  _combinedNpmrcMap.set(sourceNpmrcPath, combinedNpmrc);
-
-  return combinedNpmrc;
+  return resultLines;
 }
 
 /**
@@ -117,6 +147,7 @@ interface INpmrcTrimOptions {
   linesToPrepend?: string[];
   linesToAppend?: string[];
 }
+
 function _copyAndTrimNpmrcFile(options: INpmrcTrimOptions): string {
   const { logger, sourceNpmrcPath, targetNpmrcPath, linesToPrepend, linesToAppend } = options;
   logger.info(`Transforming ${sourceNpmrcPath}`); // Verbose
@@ -177,6 +208,7 @@ export function syncNpmrc(options: ISyncNpmrcOptions): string | undefined {
       if (!fs.existsSync(targetNpmrcFolder)) {
         fs.mkdirSync(targetNpmrcFolder, { recursive: true });
       }
+
       return _copyAndTrimNpmrcFile({
         sourceNpmrcPath,
         targetNpmrcPath,

libraries/rush-lib/src/utilities/test/npmrcUtilities.test.ts

@@ -0,0 +1,114 @@
+// Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
+// See LICENSE in the project root for license information.
+
+import { trimNpmrcFileLines } from '../npmrcUtilities';
+
+describe('npmrcUtilities', () => {
+  it(trimNpmrcFileLines.name, () => {
+    // Normal
+    expect(trimNpmrcFileLines(['var1=${foo}'], {})).toMatchInlineSnapshot(`
+Array [
+  "; MISSING ENVIRONMENT VARIABLE: var1=\${foo}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo}'], { foo: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo-fallback_value}'], {})).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo-fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo-fallback_value}'], { foo: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo-fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo:-fallback_value}'], {})).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo:-fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo:-fallback_value}'], { foo: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo:-fallback_value}",
+]
+`);
+
+    // Multiple environment variables
+    expect(trimNpmrcFileLines(['var1=${foo}-${bar}'], { foo: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "; MISSING ENVIRONMENT VARIABLE: var1=\${foo}-\${bar}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo}-${bar}'], { bar: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "; MISSING ENVIRONMENT VARIABLE: var1=\${foo}-\${bar}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo}-${bar}'], { foo: 'test', bar: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo}-\${bar}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo:-fallback_value}-${bar-fallback_value}'], {}))
+      .toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo:-fallback_value}-\${bar-fallback_value}",
+]
+`);
+
+    // Multiline
+    expect(trimNpmrcFileLines(['var1=${foo}', 'var2=${bar}'], { foo: 'test' })).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo}",
+  "; MISSING ENVIRONMENT VARIABLE: var2=\${bar}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo}', 'var2=${bar}'], { foo: 'test', bar: 'test' }))
+      .toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo}",
+  "var2=\${bar}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo}', 'var2=${bar-fallback_value}'], { foo: 'test' }))
+      .toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo}",
+  "var2=\${bar-fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo:-fallback_value}', 'var2=${bar-fallback_value}'], {}))
+      .toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo:-fallback_value}",
+  "var2=\${bar-fallback_value}",
+]
+`);
+
+    // Malformed
+    expect(trimNpmrcFileLines(['var1=${foo_fallback_value}'], {})).toMatchInlineSnapshot(`
+Array [
+  "; MISSING ENVIRONMENT VARIABLE: var1=\${foo_fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo:fallback_value}'], {})).toMatchInlineSnapshot(`
+Array [
+  "; MISSING ENVIRONMENT VARIABLE: var1=\${foo:fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo:_fallback_value}'], {})).toMatchInlineSnapshot(`
+Array [
+  "; MISSING ENVIRONMENT VARIABLE: var1=\${foo:_fallback_value}",
+]
+`);
+    expect(trimNpmrcFileLines(['var1=${foo'], {})).toMatchInlineSnapshot(`
+Array [
+  "var1=\${foo",
+]
+`);
+  });
+});