format: exclude body on CaseClause len check

fixes mvdan#217

format/format.go

@@ -594,7 +594,13 @@ func (f *fumpter) applyPre(c *astutil.Cursor) {
 			// don't move comments
 			break
 		}
-		if f.printLength(node) > shortLineLimit {
+		// check the length excluding the body
+		nodeWithoutBody := &ast.CaseClause{
+			Case:  node.Case,
+			List:  node.List,
+			Colon: node.Colon,
+		}
+		if f.printLength(nodeWithoutBody) > shortLineLimit {
 			// too long to collapse
 			break
 		}

main_test.go

@@ -26,7 +26,7 @@ var update = flag.Bool("u", false, "update testscript output files")
 func TestScripts(t *testing.T) {
 	t.Parallel()
 	p := testscript.Params{
-		Dir:           filepath.Join("testdata", "scripts"),
+		Dir:           filepath.Join("testdata", "s"),
 		UpdateScripts: *update,
 	}
 	err := gotooltest.Setup(&p)

testdata/s/short-case.txt

@@ -0,0 +1,157 @@
+gofumpt -w foo.go
+cmp foo.go foo.go.golden
+
+gofumpt -d foo.go.golden
+! stdout .
+
+-- foo.go --
+package p
+
+func f(r rune) {
+	switch r {
+	case 'a',
+		'b',
+		'c':
+
+	case 'd', 'e', 'f':
+
+	case 'a', 'b',
+		'c':
+
+	case 'v', 'e', 'r', 'y', 'l', 'o', 'n', 'g',
+		'l', 'i', 's', 't', '.', '.', '.':
+
+	// before
+	case 'a',
+		'b': // inline
+		// after
+
+	case 'a', // middle
+		'b':
+
+	case 'a', 'b', 'c', 'd', 'e', 'f',
+		'g': // very very long inline comment at the end
+
+	case 'a', 'b', 'c',
+		'd': // short comment
+	}
+	{
+		{
+			{
+				{
+					{
+						switch r {
+						case 'i', 'n', 'd', 'e',
+							'n', 't', 'e', 'd':
+						}
+					}
+				}
+			}
+		}
+	}
+}
+
+func s(x int) {
+	switch x {
+	case
+		shortConstant1,
+		shortConstant2:
+		// A comment.
+		fmt.Println(x)
+	case
+		shortConstant3,
+		shortConstant4:
+		// Do nothing.
+	default:
+		// Another comment.
+		fmt.Println(x * 2)
+	}
+}
+
+func s(x int) {
+	switch x {
+	case
+		longerConstantName1,
+		longerConstantName2:
+		// A comment.
+		fmt.Println(x)
+	case
+		longerConstantName3,
+		longerConstantName4:
+		// Do nothing.
+	default:
+		// Another comment.
+		fmt.Println(x * 2)
+	}
+}
+-- foo.go.golden --
+package p
+
+func f(r rune) {
+	switch r {
+	case 'a', 'b', 'c':
+
+	case 'd', 'e', 'f':
+
+	case 'a', 'b', 'c':
+
+	case 'v', 'e', 'r', 'y', 'l', 'o', 'n', 'g',
+		'l', 'i', 's', 't', '.', '.', '.':
+
+	// before
+	case 'a', 'b': // inline
+		// after
+
+	case 'a', // middle
+		'b':
+
+	case 'a', 'b', 'c', 'd', 'e', 'f',
+		'g': // very very long inline comment at the end
+
+	case 'a', 'b', 'c', 'd': // short comment
+	}
+	{
+		{
+			{
+				{
+					{
+						switch r {
+						case 'i', 'n', 'd', 'e',
+							'n', 't', 'e', 'd':
+						}
+					}
+				}
+			}
+		}
+	}
+}
+
+func s(x int) {
+	switch x {
+	case shortConstant1, shortConstant2:
+		// A comment.
+		fmt.Println(x)
+	case shortConstant3, shortConstant4:
+		// Do nothing.
+	default:
+		// Another comment.
+		fmt.Println(x * 2)
+	}
+}
+
+func s(x int) {
+	switch x {
+	case
+		longerConstantName1,
+		longerConstantName2:
+		// A comment.
+		fmt.Println(x)
+	case
+		longerConstantName3,
+		longerConstantName4:
+		// Do nothing.
+	default:
+		// Another comment.
+		fmt.Println(x * 2)
+	}
+}

testdata/scripts/short-case.txt

@@ -50,6 +50,23 @@ func f(r rune) {
 		}
 	}
 }
+
+func s(x int) {
+	switch x {
+	case
+		longConstantName1,
+		longConstantName2:
+		// A comment.
+		fmt.Println(x)
+	case
+		longConstantName3,
+		longConstantName4:
+		// Do nothing.
+	default:
+		// Another comment.
+		fmt.Println(x * 2)
+	}
+}
 -- foo.go.golden --
 package p
 
@@ -91,3 +108,20 @@ func f(r rune) {
 		}
 	}
 }
+
+func s(x int) {
+	switch x {
+	case
+		longConstantName1,
+		longConstantName2:
+		// A comment.
+		fmt.Println(x)
+	case
+		longConstantName3,
+		longConstantName4:
+		// Do nothing.
+	default:
+		// Another comment.
+		fmt.Println(x * 2)
+	}
+}