Add reply_schema to command json files (internal for now) (#10273)

Work in progress towards implementing a reply schema as part of COMMAND DOCS, see #9845
Since ironing the details of the reply schema of each and every command can take a long time, we
would like to merge this PR when the infrastructure is ready, and let this mature in the unstable branch.
Meanwhile the changes of this PR are internal, they are part of the repo, but do not affect the produced build.

### Background
In #9656 we add a lot of information about Redis commands, but we are missing information about the replies

### Motivation
1. Documentation. This is the primary goal.
2. It should be possible, based on the output of COMMAND, to be able to generate client code in typed
  languages. In order to do that, we need Redis to tell us, in detail, what each reply looks like.
3. We would like to build a fuzzer that verifies the reply structure (for now we use the existing
  testsuite, see the "Testing" section)

### Schema
The idea is to supply some sort of schema for the various replies of each command.
The schema will describe the conceptual structure of the reply (for generated clients), as defined in RESP3.
Note that the reply structure itself may change, depending on the arguments (e.g. `XINFO STREAM`, with
and without the `FULL` modifier)
We decided to use the standard json-schema (see https://json-schema.org/) as the reply-schema.

Example for `BZPOPMIN`:
```
"reply_schema": {
    "oneOf": [
        {
            "description": "Timeout reached and no elements were popped.",
            "type": "null"
        },
        {
            "description": "The keyname, popped member, and its score.",
            "type": "array",
            "minItems": 3,
            "maxItems": 3,
            "items": [
                {
                    "description": "Keyname",
                    "type": "string"
                },
                {
                    "description": "Member",
                    "type": "string"
                },
                {
                    "description": "Score",
                    "type": "number"
                }
            ]
        }
    ]
}
```

#### Notes
1.  It is ok that some commands' reply structure depends on the arguments and it's the caller's responsibility
  to know which is the relevant one. this comes after looking at other request-reply systems like OpenAPI,
  where the reply schema can also be oneOf and the caller is responsible to know which schema is the relevant one.
2. The reply schemas will describe RESP3 replies only. even though RESP3 is structured, we want to use reply
  schema for documentation (and possibly to create a fuzzer that validates the replies)
3. For documentation, the description field will include an explanation of the scenario in which the reply is sent,
  including any relation to arguments. for example, for `ZRANGE`'s two schemas we will need to state that one
  is with `WITHSCORES` and the other is without.
4. For documentation, there will be another optional field "notes" in which we will add a short description of
  the representation in RESP2, in case it's not trivial (RESP3's `ZRANGE`'s nested array vs. RESP2's flat
  array, for example)

Given the above:
1. We can generate the "return" section of all commands in [redis-doc](https://redis.io/commands/)
  (given that "description" and "notes" are comprehensive enough)
2. We can generate a client in a strongly typed language (but the return type could be a conceptual
  `union` and the caller needs to know which schema is relevant). see the section below for RESP2 support.
3. We can create a fuzzer for RESP3.

### Limitations (because we are using the standard json-schema)
The problem is that Redis' replies are more diverse than what the json format allows. This means that,
when we convert the reply to a json (in order to validate the schema against it), we lose information (see
the "Testing" section below).
The other option would have been to extend the standard json-schema (and json format) to include stuff
like sets, bulk-strings, error-string, etc. but that would mean also extending the schema-validator - and that
seemed like too much work, so we decided to compromise.

Examples:
1. We cannot tell the difference between an "array" and a "set"
2. We cannot tell the difference between simple-string and bulk-string
3. we cannot verify true uniqueness of items in commands like ZRANGE: json-schema doesn't cover the
  case of two identical members with different scores (e.g. `[["m1",6],["m1",7]]`) because `uniqueItems`
  compares (member,score) tuples and not just the member name. 

### Testing
This commit includes some changes inside Redis in order to verify the schemas (existing and future ones)
are indeed correct (i.e. describe the actual response of Redis).
To do that, we added a debugging feature to Redis that causes it to produce a log of all the commands
it executed and their replies.
For that, Redis needs to be compiled with `-DLOG_REQ_RES` and run with
`--reg-res-logfile <file> --client-default-resp 3` (the testsuite already does that if you run it with
`--log-req-res --force-resp3`)
You should run the testsuite with the above args (and `--dont-clean`) in order to make Redis generate
`.reqres` files (same dir as the `stdout` files) which contain request-response pairs.
These files are later on processed by `./utils/req-res-log-validator.py` which does:
1. Goes over req-res files, generated by redis-servers, spawned by the testsuite (see logreqres.c)
2. For each request-response pair, it validates the response against the request's reply_schema
  (obtained from the extended COMMAND DOCS)
5. In order to get good coverage of the Redis commands, and all their different replies, we chose to use
  the existing redis test suite, rather than attempt to write a fuzzer.

#### Notes about RESP2
1. We will not be able to use the testing tool to verify RESP2 replies (we are ok with that, it's time to
  accept RESP3 as the future RESP)
2. Since the majority of the test suite is using RESP2, and we want the server to reply with RESP3
  so that we can validate it, we will need to know how to convert the actual reply to the one expected.
   - number and boolean are always strings in RESP2 so the conversion is easy
   - objects (maps) are always a flat array in RESP2
   - others (nested array in RESP3's `ZRANGE` and others) will need some special per-command
     handling (so the client will not be totally auto-generated)

Example for ZRANGE:
```
"reply_schema": {
    "anyOf": [
        {
            "description": "A list of member elements",
            "type": "array",
            "uniqueItems": true,
            "items": {
                "type": "string"
            }
        },
        {
            "description": "Members and their scores. Returned in case `WITHSCORES` was used.",
            "notes": "In RESP2 this is returned as a flat array",
            "type": "array",
            "uniqueItems": true,
            "items": {
                "type": "array",
                "minItems": 2,
                "maxItems": 2,
                "items": [
                    {
                        "description": "Member",
                        "type": "string"
                    },
                    {
                        "description": "Score",
                        "type": "number"
                    }
                ]
            }
        }
    ]
}
```

### Other changes
1. Some tests that behave differently depending on the RESP are now being tested for both RESP,
  regardless of the special log-req-res mode ("Pub/Sub PING" for example)
2. Update the history field of CLIENT LIST
3. Added basic tests for commands that were not covered at all by the testsuite

### TODO

- [x] (maybe a different PR) add a "condition" field to anyOf/oneOf schemas that refers to args. e.g.
  when `SET` return NULL, the condition is `arguments.get||arguments.condition`, for `OK` the condition
  is `!arguments.get`, and for `string` the condition is `arguments.get` - https://github.com/redis/redis/issues/11896
- [x] (maybe a different PR) also run `runtest-cluster` in the req-res logging mode
- [x] add the new tests to GH actions (i.e. compile with `-DLOG_REQ_RES`, run the tests, and run the validator)
- [x] (maybe a different PR) figure out a way to warn about (sub)schemas that are uncovered by the output
  of the tests - https://github.com/redis/redis/issues/11897
- [x] (probably a separate PR) add all missing schemas
- [x] check why "SDOWN is triggered by misconfigured instance replying with errors" fails with --log-req-res
- [x] move the response transformers to their own file (run both regular, cluster, and sentinel tests - need to
  fight with the tcl including mechanism a bit)
- [x] issue: module API - https://github.com/redis/redis/issues/11898
- [x] (probably a separate PR): improve schemas: add `required` to `object`s - https://github.com/redis/redis/issues/11899

Co-authored-by: Ozan Tezcan <ozantezcan@gmail.com>
Co-authored-by: Hanna Fadida <hanna.fadida@redislabs.com>
Co-authored-by: Oran Agra <oran@redislabs.com>
Co-authored-by: Shaya Potter <shaya@redislabs.com>

3 files changed, 172 insertions, 5 deletions

diff --git a/tests/support/redis.tcl b/tests/support/redis.tcl
index 861e8bc27..53fa9fe91 100644
--- a/tests/support/redis.tcl
+++ b/tests/support/redis.tcl
@@ -28,6 +28,8 @@
 package require Tcl 8.5
 package provide redis 0.1
 
+source [file join [file dirname [info script]] "response_transformers.tcl"]
+
 namespace eval redis {}
 set ::redis::id 0
 array set ::redis::fd {}
@@ -41,6 +43,11 @@ array set ::redis::tls {}
 array set ::redis::callback {}
 array set ::redis::state {} ;# State in non-blocking reply reading
 array set ::redis::statestack {} ;# Stack of states, for nested mbulks
+array set ::redis::curr_argv {} ;# Remember the current argv, to be used in response_transformers.tcl
+array set ::redis::testing_resp3 {} ;# Indicating if the current client is using RESP3 (only if the test is trying to test RESP3 specific behavior. It won't be on in case of force_resp3)
+
+set ::force_resp3 0
+set ::log_req_res 0
 
 proc redis {{server 127.0.0.1} {port 6379} {defer 0} {tls 0} {tlsoptions {}} {readraw 0}} {
     if {$tls} {
@@ -62,6 +69,8 @@ proc redis {{server 127.0.0.1} {port 6379} {defer 0} {tls 0} {tlsoptions {}} {re
     set ::redis::deferred($id) $defer
     set ::redis::readraw($id) $readraw
     set ::redis::reconnect($id) 0
+    set ::redis::curr_argv($id) 0
+    set ::redis::testing_resp3($id) 0
     set ::redis::tls($id) $tls
     ::redis::redis_reset_state $id
     interp alias {} ::redis::redisHandle$id {} ::redis::__dispatch__ $id
@@ -123,6 +132,20 @@ proc ::redis::__dispatch__raw__ {id method argv} {
         set fd $::redis::fd($id)
     }
 
+    # Transform HELLO 2 to HELLO 3 if force_resp3
+    # All set the connection var testing_resp3 in case of HELLO 3
+    if {[llength $argv] > 0 && [string compare -nocase $method "HELLO"] == 0} {
+        if {[lindex $argv 0] == 3} {
+            set ::redis::testing_resp3($id) 1
+        } else {
+            set ::redis::testing_resp3($id) 0
+            if {$::force_resp3} {
+                # If we are in force_resp3 we run HELLO 3 instead of HELLO 2
+                lset argv 0 3
+            }
+        }
+    }
+
     set blocking $::redis::blocking($id)
     set deferred $::redis::deferred($id)
     if {$blocking == 0} {
@@ -146,6 +169,7 @@ proc ::redis::__dispatch__raw__ {id method argv} {
             return -code error "I/O error reading reply"
         }
 
+        set ::redis::curr_argv($id) [concat $method $argv]
         if {!$deferred} {
             if {$blocking} {
                 ::redis::redis_read_reply $id $fd
@@ -200,6 +224,8 @@ proc ::redis::__method__close {id fd} {
     catch {unset ::redis::state($id)}
     catch {unset ::redis::statestack($id)}
     catch {unset ::redis::callback($id)}
+    catch {unset ::redis::curr_argv($id)}
+    catch {unset ::redis::testing_resp3($id)}
     catch {interp alias {} ::redis::redisHandle$id {}}
 }
 
@@ -253,7 +279,7 @@ proc ::redis::redis_multi_bulk_read {id fd} {
     set err {}
     for {set i 0} {$i < $count} {incr i} {
         if {[catch {
-            lappend l [redis_read_reply $id $fd]
+            lappend l [redis_read_reply_logic $id $fd]
         } e] && $err eq {}} {
             set err $e
         }
@@ -269,8 +295,8 @@ proc ::redis::redis_read_map {id fd} {
     set err {}
     for {set i 0} {$i < $count} {incr i} {
         if {[catch {
-            set k [redis_read_reply $id $fd] ; # key
-            set v [redis_read_reply $id $fd] ; # value
+            set k [redis_read_reply_logic $id $fd] ; # key
+            set v [redis_read_reply_logic $id $fd] ; # value
             dict set d $k $v
         } e] && $err eq {}} {
             set err $e
@@ -296,13 +322,25 @@ proc ::redis::redis_read_bool fd {
     return -code error "Bad protocol, '$v' as bool type"
 }
 
+proc ::redis::redis_read_double {id fd} {
+    set v [redis_read_line $fd]
+    # unlike many other DTs, there is a textual difference between double and a string with the same value,
+    # so we need to transform to double if we are testing RESP3 (i.e. some tests check that a
+    # double reply is "1.0" and not "1")
+    if {[should_transform_to_resp2 $id]} {
+        return $v
+    } else {
+        return [expr {double($v)}]
+    }
+}
+
 proc ::redis::redis_read_verbatim_str fd {
     set v [redis_bulk_read $fd]
     # strip the first 4 chars ("txt:")
     return [string range $v 4 end]
 }
 
-proc ::redis::redis_read_reply {id fd} {
+proc ::redis::redis_read_reply_logic {id fd} {
     if {$::redis::readraw($id)} {
         return [redis_read_line $fd]
     }
@@ -314,7 +352,7 @@ proc ::redis::redis_read_reply {id fd} {
             : -
             ( -
             + {return [redis_read_line $fd]}
-            , {return [expr {double([redis_read_line $fd])}]}
+            , {return [redis_read_double $id $fd]}
             # {return [redis_read_bool $fd]}
             = {return [redis_read_verbatim_str $fd]}
             - {return -code error [redis_read_line $fd]}
@@ -340,6 +378,11 @@ proc ::redis::redis_read_reply {id fd} {
     }
 }
 
+proc ::redis::redis_read_reply {id fd} {
+    set response [redis_read_reply_logic $id $fd]
+    ::response_transformers::transform_response_if_needed $id $::redis::curr_argv($id) $response
+}
+
 proc ::redis::redis_reset_state id {
     set ::redis::state($id) [dict create buf {} mbulk -1 bulk -1 reply {}]
     set ::redis::statestack($id) {}
@@ -416,3 +459,8 @@ proc ::redis::redis_readable {fd id} {
         }
     }
 }
+
+# when forcing resp3 some tests that rely on resp2 can fail, so we have to translate the resp3 response to resp2
+proc ::redis::should_transform_to_resp2 {id} {
+    return [expr {$::force_resp3 && !$::redis::testing_resp3($id)}]
+}
diff --git a/tests/support/response_transformers.tcl b/tests/support/response_transformers.tcl
new file mode 100644
index 000000000..45b3cf8f2
--- /dev/null
+++ b/tests/support/response_transformers.tcl
@@ -0,0 +1,105 @@
+# Tcl client library - used by the Redis test
+# Copyright (C) 2009-2023 Redis Ltd.
+# Released under the BSD license like Redis itself
+#
+# This file contains a bunch of commands whose purpose is to transform
+# a RESP3 response to RESP2
+# Why is it needed?
+# When writing the reply_schema part in COMMAND DOCS we decided to use
+# the existing tests in order to verify the schemas (see logreqres.c)
+# The problem was that many tests were relying on the RESP2 structure
+# of the response (e.g. HRANDFIELD WITHVALUES in RESP2: {f1 v1 f2 v2}
+# vs. RESP3: {{f1 v1} {f2 v2}}).
+# Instead of adjusting the tests to expect RESP3 responses (a lot of
+# changes in many files) we decided to transform the response to RESP2
+# when running with --force-resp3
+
+package require Tcl 8.5
+
+namespace eval response_transformers {}
+
+# Transform a map response into an array of tuples (tuple = array with 2 elements)
+# Used for XREAD[GROUP]
+proc transfrom_map_to_tupple_array {argv response} {
+    set tuparray {}
+    foreach {key val} $response {
+        set tmp {}
+        lappend tmp $key
+        lappend tmp $val
+        lappend tuparray $tmp
+    }
+    return $tuparray
+}
+
+# Transform an array of tuples to a flat array
+proc transfrom_tuple_array_to_flat_array {argv response} {
+    set flatarray {}
+    foreach pair $response {
+        lappend flatarray {*}$pair
+    }
+    return $flatarray
+}
+
+# With HRANDFIELD, we only need to transform the response if the request had WITHVALUES
+# (otherwise the returned response is a flat array in both RESPs)
+proc transfrom_hrandfield_command {argv response} {
+    foreach ele $argv {
+        if {[string compare -nocase $ele "WITHVALUES"] == 0} {
+            return [transfrom_tuple_array_to_flat_array $argv $response]
+        }
+    }
+    return $response
+}
+
+# With some zset commands, we only need to transform the response if the request had WITHSCORES
+# (otherwise the returned response is a flat array in both RESPs)
+proc transfrom_zset_withscores_command {argv response} {
+    foreach ele $argv {
+        if {[string compare -nocase $ele "WITHSCORES"] == 0} {
+            return [transfrom_tuple_array_to_flat_array $argv $response]
+        }
+    }
+    return $response
+}
+
+# With ZPOPMIN/ZPOPMAX, we only need to transform the response if the request had COUNT (3rd arg)
+# (otherwise the returned response is a flat array in both RESPs)
+proc transfrom_zpopmin_zpopmax {argv response} {
+    if {[llength $argv] == 3} {
+        return [transfrom_tuple_array_to_flat_array $argv $response]
+    }
+    return $response
+}
+
+set ::trasformer_funcs {
+    XREAD transfrom_map_to_tupple_array
+    XREADGROUP transfrom_map_to_tupple_array
+    HRANDFIELD transfrom_hrandfield_command
+    ZRANDMEMBER transfrom_zset_withscores_command
+    ZRANGE transfrom_zset_withscores_command
+    ZRANGEBYSCORE transfrom_zset_withscores_command
+    ZRANGEBYLEX transfrom_zset_withscores_command
+    ZREVRANGE transfrom_zset_withscores_command
+    ZREVRANGEBYSCORE transfrom_zset_withscores_command
+    ZREVRANGEBYLEX transfrom_zset_withscores_command
+    ZUNION transfrom_zset_withscores_command
+    ZDIFF transfrom_zset_withscores_command
+    ZINTER transfrom_zset_withscores_command
+    ZPOPMIN transfrom_zpopmin_zpopmax
+    ZPOPMAX transfrom_zpopmin_zpopmax
+}
+
+proc ::response_transformers::transform_response_if_needed {id argv response} {
+    if {![::redis::should_transform_to_resp2 $id] || $::redis::readraw($id)} {
+        return $response
+    }
+
+    set key [string toupper [lindex $argv 0]]
+    if {![dict exists $::trasformer_funcs $key]} {
+        return $response
+    }
+
+    set transform [dict get $::trasformer_funcs $key]
+
+    return [$transform $argv $response]
+}
diff --git a/tests/support/server.tcl b/tests/support/server.tcl
index a23224bd7..4c596290d 100644
--- a/tests/support/server.tcl
+++ b/tests/support/server.tcl
@@ -207,6 +207,12 @@ proc tags_acceptable {tags err_return} {
         }
     }
 
+    # some units mess with the client output buffer so we can't really use the req-res logging mechanism.
+    if {$::log_req_res && [lsearch $tags "logreqres:skip"] >= 0} {
+        set err "Not supported when running in log-req-res mode"
+        return 0
+    }
+
     if {$::external && [lsearch $tags "external:skip"] >= 0} {
         set err "Not supported on external server"
         return 0
@@ -511,6 +517,14 @@ proc start_server {options {code undefined}} {
         dict unset config $directive
     }
 
+    if {$::log_req_res} {
+        dict set config "req-res-logfile" "stdout.reqres"
+    }
+
+    if {$::force_resp3} {
+        dict set config "client-default-resp" "3"
+    }
+
     # write new configuration to temporary file
     set config_file [tmpfile redis.conf]
     create_server_config_file $config_file $config $config_lines