Add a test case that fully wraps a function declaration.

Author: dabelknap

Tests/PrettyPrinterTests/FunctionDeclTests.swift

@@ -140,4 +140,35 @@ public class FunctionDeclTests: PrettyPrintTestCase {
 
     assertPrettyPrintEqual(input: input, expected: expected, linelength: 60)
   }
+
+  public func testFunctionFullWrap() {
+    let input =
+    """
+    public func index<Elements: Collection, Element>(of element: Element, in collection: Elements) -> Elements.Index? where Elements.Element == Element, Element: Equatable {
+      let a = 123
+      let b = "abc"
+    }
+    """
+
+    let expected =
+    """
+    public func index<
+      Elements: Collection,
+      Element
+    >(
+      of element: Element,
+      in collection: Elements
+    ) -> Elements.Index?
+    where
+      Elements.Element == Element,
+      Element: Equatable
+    {
+      let a = 123
+      let b = "abc"
+    }
+
+    """
+
+    assertPrettyPrintEqual(input: input, expected: expected, linelength: 30)
+  }
 }