Adding diff and regctl cmds to compare manifests and blobs

Signed-off-by: Brandon Mitchell <git@bmitch.net>

internal/diff/diff_test.go

@@ -0,0 +1,146 @@
+package diff
+
+import "testing"
+
+func TestDiff(t *testing.T) {
+	tests := []struct {
+		name         string
+		a, b, expect []string
+		opts         []Opt
+	}{
+		{
+			name: "empty",
+		},
+		{
+			name: "deletes",
+			a:    []string{"a", "b", "c"},
+			expect: []string{
+				"@@ -1,3 +1,0 @@",
+				"- a",
+				"- b",
+				"- c",
+			},
+		},
+		{
+			name: "inserts",
+			b:    []string{"a", "b", "c"},
+			expect: []string{
+				"@@ -1,0 +1,3 @@",
+				"+ a",
+				"+ b",
+				"+ c",
+			},
+		},
+		{
+			name: "equal",
+			a:    []string{"a", "b", "c"},
+			b:    []string{"a", "b", "c"},
+		},
+		{
+			name: "myers",
+			a:    []string{"a", "b", "c", "a", "b", "b", "a"},
+			b:    []string{"c", "b", "a", "b", "a", "c"},
+			expect: []string{
+				"@@ -1,2 +1,0 @@",
+				"- a",
+				"- b",
+				"@@ -4,0 +2,1 @@",
+				"+ b",
+				"@@ -6,1 +5,0 @@",
+				"- b",
+				"@@ -8,0 +6,1 @@",
+				"+ c",
+			},
+		},
+		{
+			name: "replace",
+			a:    []string{"a", "b", "c"},
+			b:    []string{"d", "e", "f"},
+			expect: []string{
+				"@@ -1,3 +1,3 @@",
+				"- a",
+				"- b",
+				"- c",
+				"+ d",
+				"+ e",
+				"+ f",
+			},
+		},
+		{
+			name: "change one",
+			a:    []string{"a", "b", "c", "d"},
+			b:    []string{"a", "e", "f", "d"},
+			expect: []string{
+				"@@ -2,2 +2,2 @@",
+				"- b",
+				"- c",
+				"+ e",
+				"+ f",
+			},
+		},
+		{
+			name: "context one",
+			a:    []string{"a", "b", "c", "d", "e"},
+			b:    []string{"a", "b", "f", "d", "e"},
+			opts: []Opt{WithContext(1, 1)},
+			expect: []string{
+				"@@ -2,3 +2,3 @@",
+				"  b",
+				"- c",
+				"+ f",
+				"  d",
+			},
+		},
+		{
+			name: "context three",
+			a:    []string{"a", "b", "c", "d", "e"},
+			b:    []string{"a", "b", "f", "d", "e"},
+			opts: []Opt{WithContext(3, 3)},
+			expect: []string{
+				"@@ -1,5 +1,5 @@",
+				"  a",
+				"  b",
+				"- c",
+				"+ f",
+				"  d",
+				"  e",
+			},
+		},
+		{
+			name: "context full",
+			a:    []string{"a", "b", "c", "d", "e"},
+			b:    []string{"a", "b", "f", "d", "e"},
+			opts: []Opt{WithFullContext()},
+			expect: []string{
+				"@@ -1,5 +1,5 @@",
+				"  a",
+				"  b",
+				"- c",
+				"+ f",
+				"  d",
+				"  e",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := Diff(tt.a, tt.b, tt.opts...)
+			if !strSliceEq(tt.expect, result) {
+				t.Errorf("mismatch, expected %v, received %v", tt.expect, result)
+			}
+		})
+	}
+
+}
+
+func strSliceEq(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}