cli: add and test debug decode-value

Inspired by #28995, where I needed this.

Release note: None

pkg/cli/cli_debug_test.go

@@ -0,0 +1,27 @@
+// Copyright 2018 The Cockroach Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// permissions and limitations under the License.
+
+package cli
+
+func Example_debug_decode_key_value() {
+	cliTest{}.RunWithArgs([]string{"debug", "decode-value", "016b12bd8980c0b6c2e211ba5182000172647363", "884d186d03089b09120bbd8980c0b6c2e211ba51821a0bbd8980c0b9e7c5c610e99622060801100118012206080410041802220608021002180428053004"})
+
+	// Output:
+	// debug decode-value 016b12bd8980c0b6c2e211ba5182000172647363 884d186d03089b09120bbd8980c0b6c2e211ba51821a0bbd8980c0b9e7c5c610e99622060801100118012206080410041802220608021002180428053004
+	// unable to decode key: invalid encoded mvcc key: 016b12bd8980c0b6c2e211ba5182000172647363, assuming it's a roachpb.Key with fake timestamp;
+	// if the result below looks like garbage, then it likely is:
+	//
+	// 0.987654321,0 /Local/Range/Table/53/1/-4560243296450227838/RangeDescriptor: [/Table/53/1/-4560243296450227838, /Table/53/1/-4559358311118345834)
+	// 	Raw:r1179:/Table/53/1/-45{60243296450227838-59358311118345834} [(n1,s1):1, (n4,s4):2, (n2,s2):4, next=5, gen=4]
+}