fix(cli-repl): indent multi-line help descriptions properly MONGOSH-717 (#818)

Author: addaleax

packages/cli-repl/src/format-output.spec.ts

@@ -287,6 +287,28 @@ for (const colors of [ false, true ]) {
         expect(output).to.not.contain('https://docs.mongodb.com');
         expect(output).to.contain('list available databases');
       });
+
+      it('handles multi-line descriptions', () => {
+        const output = stripAnsiColors(format({
+          value: {
+            help: 'Shell API',
+            attr: [{
+              name: 'show dbs',
+              description: 'list available\ndatabases\n\nwith line breaks'
+            }]
+          },
+          type: 'Help'
+        }));
+
+        expect(output).to.equal(`
+  Shell API:
+
+    show dbs                                   list available
+                                               databases
+
+                                               with line breaks
+`);
+      });
     });
 
     context('when the result is ExplainOutput or ExplainableCursor', () => {

packages/cli-repl/src/format-output.ts

@@ -221,7 +221,14 @@ function formatHelp(value: HelpProperties, options: FormatOptions): string {
     if (method.name && method.description) {
       formatted = `    ${method.name}`;
       const extraSpaces = argLen - formatted.length;
-      formatted += `${' '.repeat(extraSpaces)}${method.description}`;
+      const descriptionLines = method.description.split('\n');
+      descriptionLines[0] = ' '.repeat(extraSpaces) + descriptionLines[0];
+      for (let i = 1; i < descriptionLines.length; i++) {
+        if (descriptionLines[i].trim() !== '') {
+          descriptionLines[i] = ' '.repeat(argLen) + descriptionLines[i];
+        }
+      }
+      formatted += descriptionLines.join('\n');
     }
     if (!method.name && method.description) {
       formatted = `  ${method.description}`;