config: clean up and remove some tests

Small modification to make these align with our test-table-style tests.
Also removed TestCloudConfigInvalidKeys since it hasn't been a useful
test since d3294bcb86.

config/config_test.go

@@ -23,8 +23,9 @@ import (
 )
 
 func TestIsZero(t *testing.T) {
-	for _, tt := range []struct {
+	tests := []struct {
-		c     interface{}
+		c interface{}
+
 		empty bool
 	}{
 		{struct{}{}, true},
@@ -34,7 +35,9 @@ func TestIsZero(t *testing.T) {
 		{struct{ A string }{A: "hello"}, false},
 		{struct{ A int }{}, true},
 		{struct{ A int }{A: 1}, false},
-	} {
+	}
+
+	for _, tt := range tests {
 		if empty := IsZero(tt.c); tt.empty != empty {
 			t.Errorf("bad result (%q): want %t, got %t", tt.c, tt.empty, empty)
 		}
@@ -42,8 +45,9 @@ func TestIsZero(t *testing.T) {
 }
 
 func TestAssertStructValid(t *testing.T) {
-	for _, tt := range []struct {
+	tests := []struct {
-		c   interface{}
+		c interface{}
+
 		err error
 	}{
 		{struct{}{}, nil},
@@ -71,41 +75,15 @@ func TestAssertStructValid(t *testing.T) {
 		{struct {
 			A, b int `valid:"1,2"`
 		}{A: 9, b: 2}, &ErrorValid{Value: "9", Field: "A", Valid: []string{"1", "2"}}},
-	} {
+	}
+
+	for _, tt := range tests {
 		if err := AssertStructValid(tt.c); !reflect.DeepEqual(tt.err, err) {
 			t.Errorf("bad result (%q): want %q, got %q", tt.c, tt.err, err)
 		}
 	}
 }
 
-func TestCloudConfigInvalidKeys(t *testing.T) {
-	defer func() {
-		if r := recover(); r != nil {
-			t.Fatalf("panic while instantiating CloudConfig with nil keys: %v", r)
-		}
-	}()
-
-	for _, tt := range []struct {
-		contents string
-	}{
-		{"coreos:"},
-		{"ssh_authorized_keys:"},
-		{"ssh_authorized_keys:\n  -"},
-		{"ssh_authorized_keys:\n  - 0:"},
-		{"write_files:"},
-		{"write_files:\n  -"},
-		{"write_files:\n  - 0:"},
-		{"users:"},
-		{"users:\n  -"},
-		{"users:\n  - 0:"},
-	} {
-		_, err := NewCloudConfig(tt.contents)
-		if err != nil {
-			t.Fatalf("error instantiating CloudConfig with invalid keys: %v", err)
-		}
-	}
-}
-
 func TestCloudConfigUnknownKeys(t *testing.T) {
 	contents := `
 coreos: