[cli] add energy scan channel (#5677)

src/cli/README.md

@@ -1825,7 +1825,7 @@ Perform an IEEE 802.15.4 Active Scan.
 Done
 ```
 
-### scan energy \[duration\]
+### scan energy \[duration\] \[channel\]
 
 Perform an IEEE 802.15.4 Energy Scan.
 
@@ -1854,6 +1854,14 @@ Perform an IEEE 802.15.4 Energy Scan.
 Done
 ```
 
+```bash
+> scan energy 10 20
+| Ch | RSSI |
++----+------+
+| 20 |  -82 |
+Done
+```
+
 ### service
 
 Module for controlling service registration in Network Data. Each change in service registration must be sent to leader by `netdata register` command before taking effect.

src/cli/cli.cpp

@@ -3355,23 +3355,26 @@ otError Interpreter::ProcessScan(uint8_t aArgsLength, char *aArgs[])
     uint32_t scanChannels = 0;
     uint16_t scanDuration = 0;
     bool     energyScan   = false;
+    uint8_t  index        = 0;
 
     if (aArgsLength > 0)
     {
-        if (strcmp(aArgs[0], "energy") == 0)
+        if (strcmp(aArgs[index], "energy") == 0)
         {
             energyScan = true;
+            index++;
 
             if (aArgsLength > 1)
             {
-                SuccessOrExit(error = ParseAsUint16(aArgs[1], scanDuration));
+                SuccessOrExit(error = ParseAsUint16(aArgs[index++], scanDuration));
             }
         }
-        else
+
+        if (index < aArgsLength)
         {
             uint8_t channel;
 
-            SuccessOrExit(error = ParseAsUint8(aArgs[0], channel));
+            SuccessOrExit(error = ParseAsUint8(aArgs[index++], channel));
             VerifyOrExit(channel < sizeof(scanChannels) * CHAR_BIT, error = OT_ERROR_INVALID_ARGS);
             scanChannels = 1 << channel;
         }

tests/scripts/expect/cli-scan-discover.exp

@@ -75,6 +75,11 @@ for {set i 11} {$i <= 26} {incr i} {
     expect -re "\\| +$i \\| +-?\\d+ \\|"
 }
 expect "Done"
+send "scan energy 100 $channel\n"
+expect "| Ch | RSSI |"
+expect "+----+------+"
+expect -re "\\| +$channel \\| +-?\\d+ \\|"
+expect "Done"
 
 switch_node 3
 send "ifconfig up\n"