pkgs/misc: add Merge function (MR 22)

For keys/values from one dict into another

pkgs/misc/misc.go

@@ -1,4 +1,4 @@
-// Copyright 2021 Clayton Craft <clayton@craftyguy.net>
+// Copyright 2022 Clayton Craft <clayton@craftyguy.net>
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 package misc
@@ -48,3 +48,11 @@ func FreeSpace(path string) (uint64, error) {
 	size := stat.Bavail * uint64(stat.Bsize)
 	return size, nil
 }
+
+// Merge the contents of "b" into "a", overwriting any previously existing keys
+// in "a"
+func Merge(a map[string]string, b map[string]string) {
+	for k, v := range b {
+		a[k] = v
+	}
+}

pkgs/misc/misc_test.go

@@ -0,0 +1,71 @@
+// Copyright 2022 Clayton Craft <clayton@craftyguy.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package misc
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestMerge(t *testing.T) {
+	subtests := []struct {
+		name     string
+		inA      map[string]string
+		inB      map[string]string
+		expected map[string]string
+	}{
+		{
+			name: "empty B",
+			inA: map[string]string{
+				"foo":    "bar",
+				"banana": "airplane",
+			},
+			inB: map[string]string{},
+			expected: map[string]string{
+				"foo":    "bar",
+				"banana": "airplane",
+			},
+		},
+		{
+			name: "empty A",
+			inA:  map[string]string{},
+			inB: map[string]string{
+				"foo":    "bar",
+				"banana": "airplane",
+			},
+			expected: map[string]string{
+				"foo":    "bar",
+				"banana": "airplane",
+			},
+		},
+		{
+			name: "both populated, some duplicates",
+			inA: map[string]string{
+				"bar":    "bazz",
+				"banana": "yellow",
+				"guava":  "green",
+			},
+			inB: map[string]string{
+				"foo":    "bar",
+				"banana": "airplane",
+			},
+			expected: map[string]string{
+				"foo":    "bar",
+				"guava":  "green",
+				"banana": "airplane",
+				"bar":    "bazz",
+			},
+		},
+	}
+
+	for _, st := range subtests {
+		t.Run(st.name, func(t *testing.T) {
+			out := st.inA
+			Merge(out, st.inB)
+			if !reflect.DeepEqual(st.expected, out) {
+				t.Fatalf("expected: %q, got: %q\n", st.expected, out)
+			}
+		})
+	}
+}