feat util: Add silly map-merge function that should be in the stdlib

2 files changed, 99 insertions, 0 deletions

diff --git a/util/util.go b/util/util.go
new file mode 100644
index 000000000000..3d05322efb16
--- /dev/null
+++ b/util/util.go
@@ -0,0 +1,25 @@
+package util
+
+// Merges two maps together. Values from the second map override values in the first map.
+// The returned map is new if anything was changed.
+func Merge(in1 *map[string]interface{}, in2 *map[string]interface{}) *map[string]interface{} {
+	if in1 == nil || len(*in1) == 0 {
+		return in2
+	}
+
+	if in2 == nil || len(*in2) == 0 {
+		return in1
+	}
+
+
+	new := make(map[string]interface{})
+	for k, v := range *in1 {
+		new[k] = v
+	}
+
+	for k, v := range *in2 {
+		new[k] = v
+	}
+
+	return &new
+}
diff --git a/util/util_test.go b/util/util_test.go
new file mode 100644
index 000000000000..c0805533576a
--- /dev/null
+++ b/util/util_test.go
@@ -0,0 +1,74 @@
+package util
+
+import (
+	"testing"
+	"reflect"
+)
+
+func TestMergeWithEmptyMap(t *testing.T) {
+	testMap := map[string]interface{}{
+		"foo": "bar",
+	}
+
+	empty := make(map[string]interface{})
+
+	res1 := Merge(&testMap, &empty)
+	res2 := Merge(&empty, &testMap)
+
+	if res1 != &testMap || res2 != &testMap {
+		t.Error("A new map was returned incorrectly.")
+		t.Fail()
+	}
+}
+
+func TestMergeWithNilMap(t *testing.T) {
+	testMap := map[string]interface{}{
+		"foo": "bar",
+	}
+
+	res1 := Merge(&testMap, nil)
+	res2 := Merge(nil, &testMap)
+
+	if res1 != &testMap || res2 != &testMap {
+		t.Error("A new map was returned incorrectly.")
+		t.Fail()
+	}
+}
+
+func TestMergeMaps(t *testing.T) {
+	map1 := map[string]interface{}{
+		"foo": "bar",
+	}
+
+	map2 := map[string]interface{}{
+		"bar": "baz",
+	}
+
+	result := Merge(&map1, &map2)
+	expected := map[string]interface{}{
+		"foo": "bar",
+		"bar": "baz",
+	}
+
+	if !reflect.DeepEqual(*result, expected) {
+		t.Error("Maps were merged incorrectly.")
+		t.Fail()
+	}
+}
+
+func TestMergeMapsPrecedence(t *testing.T) {
+	map1 := map[string]interface{}{
+		"foo": "incorrect",
+	}
+
+	map2 := map[string]interface{}{
+		"foo": "correct",
+	}
+
+	result := Merge(&map1, &map2)
+
+	if (*result)["foo"] != "correct" {
+		t.Error("Map merge precedence test failed.")
+		t.Fail()
+	}
+}