refactor: redirect subsequent imports of "source-map-support" to this…

source-map-support.d.ts

@@ -31,6 +31,16 @@ export interface Options {
     overrideRetrieveSourceMap?: boolean | undefined;
     retrieveFile?(path: string): string;
     retrieveSourceMap?(source: string): UrlAndMap | null;
+    /**
+     * Set false to disable redirection of require / import `source-map-support` to `@cspotcode/source-map-support`
+     */
+    redirectConflictingLibrary?: boolean;
+    /**
+     * Callback will be called every time we redirect due to `redirectConflictingLibrary`
+     * This allows consumers to log helpful warnings if they choose.
+     * @param parent NodeJS.Module which made the require() or require.resolve() call
+     */
+    onConflictingLibraryRedirect?: (request: string, parent: any, isMain: boolean, redirectedRequest: string) => void;
 }
 
 export interface Position {

source-map-support.js

@@ -77,6 +77,11 @@ var sharedData = initializeSharedData({
   errorPrepareStackTraceHook: undefined,
   /** @type {HookState} */
   processEmitHook: undefined,
+  /** @type {HookState} */
+  moduleResolveFilenameHook: undefined,
+
+  /** @type {Array<(request: string, parent: any, isMain: boolean, redirectedRequest: string) => void>} */
+  onConflictingLibraryRedirectArr: [],
 
   // If true, the caches are reset before a stack trace formatting operation
   emptyCacheBetweenOperations: false,
@@ -633,6 +638,47 @@ exports.install = function(options) {
     }
   }
 
+  // Use dynamicRequire to avoid including in browser bundles
+  var Module = dynamicRequire(module, 'module');
+
+  // Redirect subsequent imports of "source-map-support"
+  // to this package
+  const {redirectConflictingLibrary = true, onConflictingLibraryRedirect} = options;
+  if(redirectConflictingLibrary) {
+    if (!sharedData.moduleResolveFilenameHook) {
+      const originalValue = Module._resolveFilename;
+      const moduleResolveFilenameHook = sharedData.moduleResolveFilenameHook = {
+        enabled: true,
+        originalValue,
+        installedValue: undefined,
+      }
+      Module._resolveFilename = sharedData.moduleResolveFilenameHook.installedValue = function (request, parent, isMain, options) {
+        if (moduleResolveFilenameHook.enabled) {
+          // Match all source-map-support entrypoints: source-map-support, source-map-support/register
+          let requestRedirect;
+          if (request === 'source-map-support') {
+            requestRedirect = './';
+          } else if (request === 'source-map-support/register') {
+            requestRedirect = './register';
+          }
+
+          if (requestRedirect !== undefined) {
+              const newRequest = require.resolve(requestRedirect);
+              for (const cb of sharedData.onConflictingLibraryRedirectArr) {
+                cb(request, parent, isMain, options, newRequest);
+              }
+              request = newRequest;
+          }
+        }
+
+        return originalValue.call(this, request, parent, isMain, options);
+      }
+    } 
+    if (onConflictingLibraryRedirect) {
+      sharedData.onConflictingLibraryRedirectArr.push(onConflictingLibraryRedirect);
+    }
+  }
+
   // Allow sources to be found by methods other than reading the files
   // directly from disk.
   if (options.retrieveFile) {
@@ -655,8 +701,6 @@ exports.install = function(options) {
 
   // Support runtime transpilers that include inline source maps
   if (options.hookRequire && !isInBrowser()) {
-    // Use dynamicRequire to avoid including in browser bundles
-    var Module = dynamicRequire(module, 'module');
     var $compile = Module.prototype._compile;
 
     if (!$compile.__sourceMapSupport) {
@@ -738,6 +782,17 @@ exports.uninstall = function() {
     }
     sharedData.errorPrepareStackTraceHook = undefined;
   }
+  if (sharedData.moduleResolveFilenameHook) {
+    // Disable behavior
+    sharedData.moduleResolveFilenameHook.enabled = false;
+    // If possible, remove our hook function.  May not be possible if subsequent third-party hooks have wrapped around us.
+    var Module = dynamicRequire(module, 'module');
+    if(Module._resolveFilename === sharedData.moduleResolveFilenameHook.installedValue) {
+      Module._resolveFilename = sharedData.moduleResolveFilenameHook.originalValue;
+    }
+    sharedData.moduleResolveFilenameHook = undefined;
+  }
+  sharedData.onConflictingLibraryRedirectArr.length = 0;
 }
 
 exports.resetRetrieveHandlers = function() {

test.js

@@ -1,8 +1,10 @@
 // Note: some tests rely on side-effects from prior tests.
 // You may not get meaningful results running a subset of tests.
 
+const Module = require('module');
 const priorErrorPrepareStackTrace = Error.prepareStackTrace;
 const priorProcessEmit = process.emit;
+const priorResolveFilename = Module._resolveFilename;
 const underTest = require('./source-map-support');
 var SourceMapGenerator = require('source-map').SourceMapGenerator;
 var child_process = require('child_process');
@@ -704,16 +706,52 @@ it('supports multiple instances', function(done) {
   ]);
 });
 
+describe('redirects require() of "source-map-support" to this module', function() {
+  it('redirects', function() {
+    assert.strictEqual(require.resolve('source-map-support'), require.resolve('.'));
+    assert.strictEqual(require.resolve('source-map-support/register'), require.resolve('./register'));
+    assert.strictEqual(require('source-map-support'), require('.'));
+  });
+
+  it('emits notifications', function() {
+    let onConflictingLibraryRedirectCalls = [];
+    let onConflictingLibraryRedirectCalls2 = [];
+    underTest.install({
+      onConflictingLibraryRedirect(request, parent, isMain, redirectedRequest) {
+        onConflictingLibraryRedirectCalls.push([...arguments]);
+      }
+    });
+    underTest.install({
+      onConflictingLibraryRedirect(request, parent, isMain, redirectedRequest) {
+        onConflictingLibraryRedirectCalls2.push([...arguments]);
+      }
+    });
+    require.resolve('source-map-support');
+    assert.strictEqual(onConflictingLibraryRedirectCalls.length, 1);
+    assert.strictEqual(onConflictingLibraryRedirectCalls2.length, 1);
+    for(const args of [onConflictingLibraryRedirectCalls[0], onConflictingLibraryRedirectCalls2[0]]) {
+      const [request, parent, isMain, options, redirectedRequest] = args;
+      assert.strictEqual(request, 'source-map-support');
+      assert.strictEqual(parent, module);
+      assert.strictEqual(isMain, false);
+      assert.strictEqual(options, undefined);
+      assert.strictEqual(redirectedRequest, require.resolve('.'));
+    }
+  });
+});
+
 describe('uninstall', function() {
   this.beforeEach(function() {
     underTest.uninstall();
     process.emit = priorProcessEmit;
     Error.prepareStackTrace = priorErrorPrepareStackTrace;
+    Module._resolveFilename = priorResolveFilename;
   });
 
   it('uninstall removes hooks and source-mapping behavior', function() {
     assert.strictEqual(Error.prepareStackTrace, priorErrorPrepareStackTrace);
     assert.strictEqual(process.emit, priorProcessEmit);
+    assert.strictEqual(Module._resolveFilename, priorResolveFilename);
     normalThrowWithoutSourceMapSupportInstalled();
   });
 
@@ -773,4 +811,20 @@ describe('uninstall', function() {
     process.emit('foo');
     assert(peInvocations >= 1);
   });
+
+  it('uninstall preserves third-party module._resolveFilename hooks installed after us', function() {
+    installSms();
+    const wrappedResolveFilename = Module._resolveFilename;
+    let peInvocations = 0;
+    function thirdPartyModuleResolveFilename() {
+      peInvocations++;
+      return wrappedResolveFilename.apply(this, arguments);
+    }
+    Module._resolveFilename = thirdPartyModuleResolveFilename;
+    underTest.uninstall();
+    assert.strictEqual(Module._resolveFilename, thirdPartyModuleResolveFilename);
+    normalThrowWithoutSourceMapSupportInstalled();
+    Module._resolveFilename('repl');
+    assert(peInvocations >= 1);
+  });
 });