chore: move load() __filename and __dirname handling to shell-api (#710)

This will make it easier to implement these features in a fully
equivalent way in Compass/VSCode, without having to duplicate this
particular bit of code (and not risk divergence, e.g. if we should
ever decide to use a separate stack for storing filename info).

Author: addaleax

packages/cli-repl/src/mongosh-repl.ts

@@ -3,13 +3,12 @@ import { MongoshCommandFailed, MongoshInternalError, MongoshWarning } from '@mon
 import { changeHistory } from '@mongosh/history';
 import i18n from '@mongosh/i18n';
 import type { ServiceProvider } from '@mongosh/service-provider-core';
-import { EvaluationListener, ShellCliOptions, ShellInternalState } from '@mongosh/shell-api';
+import { EvaluationListener, ShellCliOptions, ShellInternalState, OnLoadResult } from '@mongosh/shell-api';
 import { ShellEvaluator, ShellResult } from '@mongosh/shell-evaluator';
 import type { MongoshBus, UserConfig } from '@mongosh/types';
 import askpassword from 'askpassword';
 import { Console } from 'console';
 import { once } from 'events';
-import path from 'path';
 import prettyRepl from 'pretty-repl';
 import { ReplOptions, REPLServer } from 'repl';
 import type { Readable, Writable } from 'stream';
@@ -318,27 +317,17 @@ class MongoshNodeRepl implements EvaluationListener {
     }
   }
 
-  async onLoad(filename: string): Promise<void> {
+  async onLoad(filename: string): Promise<OnLoadResult> {
     const repl = this.runtimeState().repl;
     const {
       contents,
       absolutePath
     } = await this.ioProvider.readFileUTF8(filename);
 
-    const previousFilename = repl.context.__filename;
-    repl.context.__filename = absolutePath;
-    repl.context.__dirname = path.dirname(absolutePath);
-    try {
-      await promisify(repl.eval.bind(repl))(contents, repl.context, filename);
-    } finally {
-      if (previousFilename) {
-        repl.context.__filename = previousFilename;
-        repl.context.__dirname = path.dirname(previousFilename);
-      } else {
-        delete repl.context.__filename;
-        delete repl.context.__dirname;
-      }
-    }
+    return {
+      resolvedFilename: absolutePath,
+      evaluate: () => promisify(repl.eval.bind(repl))(contents, repl.context, absolutePath)
+    };
   }
 
   /**

packages/shell-api/src/index.ts

@@ -5,7 +5,7 @@ import Database from './database';
 import Explainable from './explainable';
 import ExplainableCursor from './explainable-cursor';
 import Help, { HelpProperties } from './help';
-import ShellInternalState, { EvaluationListener, ShellCliOptions } from './shell-internal-state';
+import ShellInternalState, { EvaluationListener, ShellCliOptions, OnLoadResult } from './shell-internal-state';
 import toIterator from './toIterator';
 import Shard from './shard';
 import ReplicaSet from './replica-set';
@@ -62,5 +62,6 @@ export {
   getShellApiType,
   ShellResult,
   ShellCliOptions,
-  TypeSignature
+  TypeSignature,
+  OnLoadResult
 };

packages/shell-api/src/shell-api.spec.ts

@@ -570,9 +570,22 @@ describe('ShellApi', () => {
     });
     describe('load', () => {
       it('asks the evaluation listener to load a file', async() => {
-        evaluationListener.onLoad.resolves();
+        evaluationListener.onLoad.callsFake(async(filename: string) => {
+          expect(filename).to.equal('abc.js');
+          expect(internalState.context.__filename).to.equal(undefined);
+          expect(internalState.context.__dirname).to.equal(undefined);
+          return {
+            resolvedFilename: '/resolved/abc.js',
+            evaluate: async() => {
+              expect(internalState.context.__filename).to.equal('/resolved/abc.js');
+              expect(internalState.context.__dirname).to.equal('/resolved');
+            }
+          };
+        });
         await internalState.context.load('abc.js');
-        expect(evaluationListener.onLoad).to.have.been.calledWith('abc.js');
+        expect(evaluationListener.onLoad).to.have.callCount(1);
+        expect(internalState.context.__filename).to.equal(undefined);
+        expect(internalState.context.__dirname).to.equal(undefined);
       });
     });
     for (const cmd of ['print', 'printjson']) {

packages/shell-api/src/shell-api.ts

@@ -20,6 +20,7 @@ import { CommonErrors, MongoshUnimplementedError, MongoshInternalError } from '@
 import { DBQuery } from './deprecated';
 import { promisify } from 'util';
 import { ClientSideFieldLevelEncryptionOptions } from './field-level-encryption';
+import { dirname } from 'path';
 
 @shellApiClassDefault
 @hasAsyncChild
@@ -109,7 +110,25 @@ export default class ShellApi extends ShellApiClass {
         CommonErrors.NotImplemented
       );
     }
-    await this.internalState.evaluationListener.onLoad(filename);
+    const {
+      resolvedFilename, evaluate
+    } = await this.internalState.evaluationListener.onLoad(filename);
+
+    const context = this.internalState.context;
+    const previousFilename = context.__filename;
+    context.__filename = resolvedFilename;
+    context.__dirname = dirname(resolvedFilename);
+    try {
+      await evaluate();
+    } finally {
+      if (previousFilename) {
+        context.__filename = previousFilename;
+        context.__dirname = dirname(previousFilename);
+      } else {
+        delete context.__filename;
+        delete context.__dirname;
+      }
+    }
     return true;
   }
 

packages/shell-api/src/shell-internal-state.ts

@@ -35,6 +35,19 @@ export interface AutocompleteParameters {
   getCollectionCompletionsForCurrentDb: (collName: string) => Promise<string[]>;
 }
 
+export interface OnLoadResult {
+  /**
+   * The absolute path of the file that should be load()ed.
+   */
+  resolvedFilename: string;
+
+  /**
+   * The actual steps that are needed to evaluate the load()ed file.
+   * For the duration of this call, __filename and __dirname are set as expected.
+   */
+  evaluate(): Promise<void>;
+}
+
 export interface EvaluationListener {
   /**
    * Called when print() or printjson() is run from the shell.
@@ -66,7 +79,7 @@ export interface EvaluationListener {
   /**
    * Called when load() is used in the shell.
    */
-  onLoad?: (filename: string) => Promise<void>;
+  onLoad?: (filename: string) => Promise<OnLoadResult> | OnLoadResult;
 }
 
 /**