I would like to know if there is not Fortigates an equivalent of the packet-tracer command that we can find on the ASA.

Here is an example of execution for those who don't know it:

NAT and pass :

lev5505# packet-tracer input inside tcp 192.168.3.20 9876 8.8.8.8 80

Phase: 1
Type: ACCESS-LIST
Subtype: 
Result: ALLOW
Config:
Implicit Rule
Additional Information:
MAC Access list

Phase: 2
Type: ROUTE-LOOKUP
Subtype: input
Result: ALLOW
Config:
Additional Information:
in   0.0.0.0         0.0.0.0         outside

Phase: 3
Type: ACCESS-LIST
Subtype: log
Result: ALLOW
Config:
access-group inside-in in interface inside
access-list inside-in extended permit tcp any any eq www 
access-list inside-in remark Allows DNS
Additional Information:

Phase: 4
Type: IP-OPTIONS
Subtype: 
Result: ALLOW
Config:
Additional Information:

Phase: 5
Type: VPN
Subtype: ipsec-tunnel-flow
Result: ALLOW
Config:
Additional Information:

Phase: 6
Type: NAT
Subtype: 
Result: ALLOW
Config:
object network inside-network
 nat (inside,outside) dynamic interface
Additional Information:
Dynamic translate 192.168.3.20/9876 to 81.56.15.183/9876

Phase: 7
Type: IP-OPTIONS
Subtype: 
Result: ALLOW
Config:
Additional Information:

Phase: 8
Type: FLOW-CREATION
Subtype: 
Result: ALLOW
Config:
Additional Information:
New flow created with id 94755, packet dispatched to next module

Result:
input-interface: inside
input-status: up
input-line-status: up
output-interface: outside
output-status: up
output-line-status: up
Action: allow

Blocked by ACL:

lev5505# packet-tracer input inside tcp 192.168.3.20 9876 8.8.8.8 81

Phase: 1
Type: ROUTE-LOOKUP
Subtype: input
Result: ALLOW
Config:
Additional Information:
in   0.0.0.0         0.0.0.0         outside

Phase: 2
Type: ACCESS-LIST
Subtype: 
Result: DROP
Config:
Implicit Rule
Additional Information:

Result:
input-interface: inside
input-status: up
input-line-status: up
output-interface: outside
output-status: up
output-line-status: up
Action: drop
Drop-reason: (acl-drop) Flow is denied by configured rule

Is there any equivalent on the Fortigates ?