feat(shell): support whitespace-only commands (#4864)

Author: paul-soporan

Diff for: .yarn/versions/038526b5.yml

@@ -0,0 +1,26 @@
+releases:
+  "@yarnpkg/cli": minor
+  "@yarnpkg/parsers": minor
+  "@yarnpkg/shell": minor
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/core"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/sdks"

Diff for: CHANGELOG.md

@@ -71,6 +71,10 @@ The following changes only affect people writing Yarn plugins:
 
 - The patched filesystem now supports `fchown`.
 
+### Shell
+
+- The builtin shell now supports whitespace-only commands.
+
 ## 3.2.3
 
 ### Bugfixes

Diff for: packages/yarnpkg-parsers/sources/grammars/shell.js

@@ -1,5 +1,5 @@
 Start
-  = line:ShellLine? { return line ? line : [] }
+  = S* line:ShellLine? { return line ? line : [] }
 
 ShellLine
   = command:CommandLine S* type:ShellLineType then:ShellLineThen? { return [ { command, type } ].concat(then || []) }

Diff for: packages/yarnpkg-parsers/sources/grammars/shell.pegjs

@@ -45,6 +45,16 @@ const VALID_COMMANDS = [
 ];
 
 const INVALID_COMMANDS = [
+  // Empty shell lines
+  ...[
+    // Only fish supports these
+    `;;`,
+    `echo foo;;`,
+    // Only zsh and fish support these
+    `; ;`,
+    `echo foo; ;`,
+  ],
+
   `echo }`,
   `echo foo}`,
 
@@ -127,8 +137,8 @@ describe(`Shell parser`, () => {
     });
   });
 
-  describe(`String parse`, () => {
-    it(`should parse parse double quote string currectly`, () => {
+  describe(`Strings`, () => {
+    it(`should parse double quoted strings correctly`, () => {
       for (const [original, raw] of DOUBLE_QUOTE_STRING_ESCAPE_TESTS) {
         expect(parseShell(`echo "${original}"`)).toStrictEqual([expect.objectContaining({
           command: expect.objectContaining({
@@ -143,7 +153,7 @@ describe(`Shell parser`, () => {
       }
     });
 
-    it(`should parse parse ANSI-C quote string currectly`, () => {
+    it(`should parse ANSI-C strings correctly`, () => {
       for (const [original, raw] of ANSI_C_STRING_ESCAPE_TESTS) {
         expect(parseShell(`echo $'${original}'`)).toStrictEqual([expect.objectContaining({
           command: expect.objectContaining({

Diff for: packages/yarnpkg-parsers/tests/shell.test.ts

@@ -87,22 +87,54 @@ const bufferResult = async (command: string, args: Array<string> = [], options:
 
 describe(`Shell`, () => {
   describe(`Simple shell features`, () => {
-    it(`should support an empty string`, async () => {
-      await expect(bufferResult(
-        ``,
-      )).resolves.toMatchObject({
+    describe(`Empty commands`, () => {
+      const EMPTY_COMMAND_RESULT = {
         exitCode: 0,
         stdout: ``,
+      };
+
+      it(`should support an empty string`, async () => {
+        await expect(bufferResult(
+          ``,
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
       });
-    });
 
-    it(`should support an empty string when passing arguments`, async () => {
-      await expect(bufferResult(
-        ``,
-        [`hello`, `world`],
-      )).resolves.toMatchObject({
-        exitCode: 0,
-        stdout: ``,
+      it(`should support a whitespace-only string`, async () => {
+        await expect(bufferResult(
+          ` `,
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
+
+        await expect(bufferResult(
+          `\t`,
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
+
+        await expect(bufferResult(
+          `  \t   \t   \t  `,
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
+      });
+
+      it(`should support an empty string when passing arguments`, async () => {
+        await expect(bufferResult(
+          ``,
+          [`hello`, `world`],
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
+      });
+
+      it(`should support a whitespace-only string when passing arguments`, async () => {
+        await expect(bufferResult(
+          ` `,
+          [`hello`, `world`],
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
+
+        await expect(bufferResult(
+          `\t`,
+          [`hello`, `world`],
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
+
+        await expect(bufferResult(
+          `  \t   \t   \t  `,
+          [`hello`, `world`],
+        )).resolves.toMatchObject(EMPTY_COMMAND_RESULT);
       });
     });