feat: support option parsing for grep -C flag

This adds support for shelljs/shelljs#1206. This
requires special parsing logic on the shx side.

Test: npm test
Test: ./lib/cli.js grep -A 1 'foo' ~/foobartest.txt
Test: cat ~/foobartest.txt | ./lib/cli.js grep -A 1 'foo'

Author: nfischer

src/config.js

@@ -54,6 +54,15 @@ export const shouldReadStdin = (args) => {
   if (parsedArgs.n && (cmd === 'head' || cmd === 'tail')) {
     requiredNumArgs++;
   }
+  if ((parsedArgs.A || parsedArgs.B || parsedArgs.C) && cmd === 'grep') {
+    requiredNumArgs++;
+  }
 
-  return Boolean(!process.stdin.isTTY && parsedArgs._.length < requiredNumArgs);
+  if (process.stdin.isTTY) {
+    return false;
+  }
+  if (parsedArgs._.length >= requiredNumArgs) {
+    return false;
+  }
+  return true;
 };

test/specs/cli.js

@@ -193,6 +193,9 @@ describe('cli', () => {
       shouldReadStdin(['head', '-n', '1']).should.equal(true);
       shouldReadStdin(['tail', '-n', '1']).should.equal(true);
       shouldReadStdin(['grep', '-i', 'a.*z']).should.equal(true);
+      shouldReadStdin(['grep', '-A', 2, 'a.*z']).should.equal(true);
+      shouldReadStdin(['grep', '-B', 2, 'a.*z']).should.equal(true);
+      shouldReadStdin(['grep', '-C', 2, 'a.*z']).should.equal(true);
     });
 
     it('does not read stdin if process.stdin is a TTY', () => {
@@ -433,10 +436,20 @@ describe('cli', () => {
     afterEach(() => {
       shell.rm('-f', testFileName);
     });
+
     it('works with regex syntax', () => {
       const ret = cli('grep', 'fo*', testFileName);
       ret.stdout.should.equal('foo\nf\nsomething foo\n');
     });
+
+    it('correctly parses -A/-B/-C flags', () => {
+      let ret = cli('grep', '-A', '1', 'foo', testFileName);
+      ret.stdout.should.equal('foo\nf\n--\nsomething foo\n');
+      ret = cli('grep', '-B', '1', 'foo', testFileName);
+      ret.stdout.should.equal('1st line\nfoo\n--\ndoes not match\nsomething foo\n');
+      ret = cli('grep', '-C', '1', 'foo', testFileName);
+      ret.stdout.should.equal('1st line\nfoo\nf\ndoes not match\nsomething foo\n');
+    });
   });
 
   describe('chmod', () => {