Handle long state variable declarations (#388)

Author: fvictorio

src/nodes/StateVariableDeclaration.js

@@ -1,11 +1,22 @@
 const {
   doc: {
-    builders: { concat }
+    builders: { concat, group, indent, line }
   }
 } = require('prettier/standalone');
 
-const initialValue = (node, path, print) =>
-  node.initialValue ? concat([' = ', path.call(print, 'initialValue')]) : '';
+const initialValue = (node, path, print) => {
+  if (!node.initialValue) {
+    return '';
+  }
+
+  if (node.initialValue.type === 'TupleExpression') {
+    return concat([' = ', path.call(print, 'initialValue')]);
+  }
+
+  return group(
+    concat([' =', indent(concat([line, path.call(print, 'initialValue')]))])
+  );
+};
 
 const StateVariableDeclaration = {
   print: ({ node, path, print }) =>

tests/StateVariableDeclarations/StateVariableDeclarations.sol

@@ -0,0 +1,3 @@
+contract Contract {
+  bytes32 private constant DOMAIN_SEPARATOR_TYPEHASH = 0x035aff83d86937d35b32e04f0ddc6ff469290eef2f1b692d8a815c89404d4749;
+}

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

@@ -0,0 +1,13 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`StateVariableDeclarations.sol 1`] = `
+contract Contract {
+  bytes32 private constant DOMAIN_SEPARATOR_TYPEHASH = 0x035aff83d86937d35b32e04f0ddc6ff469290eef2f1b692d8a815c89404d4749;
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+contract Contract {
+    bytes32 private constant DOMAIN_SEPARATOR_TYPEHASH =
+        0x035aff83d86937d35b32e04f0ddc6ff469290eef2f1b692d8a815c89404d4749;
+}
+
+`;

tests/StateVariableDeclarations/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname);