clang-format: [JS] prefer wrapping chains over empty literals.

[mprobst]

Summary

E.g. don't wrap like this:

(foo.bar.baz).and.bam(Blah.of({
}))

But rather:

(foo.bar.baz)
    .and.bam(Blah.of({}))

[djasper]

lib/Format/TokenAnnotator.cpp

2009

Or just Left.opensScope() && Right.closesScope()?

Technically, that's probably not the same thing, but otherwise you have unmatched brackets and that's bad no matter what, no?

lib/Format/TokenAnnotator.cpp

unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
   } else if (Style.Language == FormatStyle::LK_JavaScript) {
     if (Right.is(Keywords.kw_function) && Left.isNot(tok::comma))
       return 100;
     if (Left.is(TT_JsTypeColon))
       return 35;
     if ((Left.is(TT_TemplateString) && Left.TokenText.endswith("${")) ||
         (Right.is(TT_TemplateString) && Right.TokenText.startswith("}")))
       return 100;
+    // Prefer breaking call chains (".foo") over empty "{}", "[]" or "()".
+    if ((Left.is(tok::l_brace) && Right.is(tok::r_brace)) ||
+        (Left.is(tok::l_square) && Right.is(tok::r_square)) ||
+        (Left.is(tok::l_paren) && Right.is(tok::r_paren)))
+      return 200;
   }
 
   if (Right.is(tok::identifier) && Right.Next && Right.Next->is(TT_DictLiteral))
     return 1;
   if (Right.is(tok::l_square)) {
     if (Style.Language == FormatStyle::LK_Proto)
       return 1;
     if (Left.is(tok::r_square))

unittests/Format/FormatTestJS.cpp

TEST_F(FormatTestJS, FunctionLiterals) {
   Style.ColumnLimit = 32;
   verifyFormat("f({\n"
                "  a: function() { return 1; }\n"
                "});",
                Style);
 
 }
 
+TEST_F(FormatTestJS, DontWrapEmptyLiterals) {
+  verifyFormat("(aaaaaaaaaaaaaaaaaaaaa.getData as jasmine.Spy)\n"
+               "    .and.returnValue(Observable.of([]));");
+  verifyFormat("(aaaaaaaaaaaaaaaaaaaaa.getData as jasmine.Spy)\n"
+               "    .and.returnValue(Observable.of({}));");
+  verifyFormat("(aaaaaaaaaaaaaaaaaaaaa.getData as jasmine.Spy)\n"
+               "    .and.returnValue(Observable.of(()));");
+}
+
 TEST_F(FormatTestJS, InliningFunctionLiterals) {
   FormatStyle Style = getGoogleStyle(FormatStyle::LK_JavaScript);
   Style.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
   verifyFormat("var func = function() {\n"
                "  return 1;\n"
                "};",
                Style);
   verifyFormat("var func = doSomething(function() { return 1; });", Style);