Add space around ~ combinator (#1774)

src/printer.js

@@ -2612,7 +2612,7 @@ function genericPrintNoParens(path, options, print, args) {
       ]);
     }
     case "selector-combinator": {
-      if (n.value === "+" || n.value === ">") {
+      if (n.value === "+" || n.value === ">" || n.value === "~") {
         return concat([" ", n.value, " "]);
       }
       return n.value;

tests/css_combinator/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,10 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`combinator.css 1`] = `
+-Option/root .public/section ~ .public/section:before {
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+-Option/root .public/section ~ .public/section:before {
+}
+
+`;

tests/css_combinator/combinator.css

@@ -0,0 +1,2 @@
+-Option/root .public/section ~ .public/section:before {
+}

tests/css_combinator/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "postcss" });

tests/stylefmt/custom-properties/__snapshots__/jsfmt.spec.js.snap

@@ -2,7 +2,7 @@
 
 exports[`custom-properties.css 1`] = `
 :root{--mainColor:#123456}
-a{color:var      (        --mainColor     )     ; }
+a{color:var(        --mainColor     )     ; }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 :root {
   --mainColor: #123456;

tests/stylefmt/var-notation/__snapshots__/jsfmt.spec.js.snap

@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`var-notation.css 1`] = `
-.foo {margin:var  (     --n-gutterSize) 0 var    (   --gutterSize ) var( --n-gutterSize );
+.foo {margin:var(     --n-gutterSize) 0 var(   --gutterSize ) var( --n-gutterSize );
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 .foo {