cmd/schemagen: refactoring

- Replace log.Faltal with error wrapping in schemagen func
- Simplify tests, use temp dir and ioutil functions, remove boilerplate code
- In test use schemagen keyspace to avoid name conflict with examples
- Change template

cmd/schemagen/camelize_test.go

@@ -0,0 +1,31 @@
+// Copyright (C) 2017 ScyllaDB
+// Use of this source code is governed by a ALv2-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "testing"
+
+func TestCamelize(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+	}{
+		{"hello", "Hello"},
+		{"_hello", "Hello"},
+		{"__hello", "Hello"},
+		{"hello_", "Hello"},
+		{"hello_world", "HelloWorld"},
+		{"hello__world", "HelloWorld"},
+		{"_hello_world", "HelloWorld"},
+		{"helloWorld", "HelloWorld"},
+		{"HelloWorld", "HelloWorld"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			if got := camelize(tt.input); got != tt.want {
+				t.Errorf("camelize() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}