Added custom CheckType & clarified panic behavior in docs

README.md

@@ -27,12 +27,14 @@ Four main API methods are offered:
 
 * `process_instruction`: Process an instruction and return the result.
 * `process_and_validate_instruction`: Process an instruction and perform a
-  series of checks on the result, panicking if any checks fail.
+  series of checks on the result. By default, failing checks cause a panic,
+  but this behavior is configurable through `Mollusk::config`.
 * `process_instruction_chain`: Process a chain of instructions and return
   the result.
 * `process_and_validate_instruction_chain`: Process a chain of instructions
-  and perform a series of checks on each result, panicking if any checks
-  fail.
+  and perform a series of checks on each result. By default, failing checks
+  cause a panic, but this behavior is configurable through
+  `Mollusk::config`.
 
 ## Single Instructions
 

harness/src/lib.rs

@@ -27,12 +27,14 @@
 //!
 //! * `process_instruction`: Process an instruction and return the result.
 //! * `process_and_validate_instruction`: Process an instruction and perform a
-//!   series of checks on the result, panicking if any checks fail.
+//!   series of checks on the result. By default, failing checks cause a panic,
+//!   but this behavior is configurable through `Mollusk::config`.
 //! * `process_instruction_chain`: Process a chain of instructions and return
 //!   the result.
 //! * `process_and_validate_instruction_chain`: Process a chain of instructions
-//!   and perform a series of checks on each result, panicking if any checks
-//!   fail.
+//!   and perform a series of checks on each result. By default, failing checks
+//!   cause a panic, but this behavior is configurable through
+//!   `Mollusk::config`.
 //!
 //! ## Single Instructions
 //!

result/src/check.rs

@@ -5,12 +5,14 @@ use {
         config::{compare, throw, CheckContext, Config},
         types::{InstructionResult, ProgramResult},
     },
-    solana_account::ReadableAccount,
+    solana_account::{Account, ReadableAccount},
     solana_instruction::error::InstructionError,
     solana_program_error::ProgramError,
     solana_pubkey::Pubkey,
 };
 
+type AccountCheckFn = dyn Fn(&[(Pubkey, Account)]) -> bool;
+
 enum CheckType<'a> {
     /// Check the number of compute units consumed by the instruction.
     ComputeUnitsConsumed(u64),
@@ -22,8 +24,10 @@ enum CheckType<'a> {
     ReturnData(&'a [u8]),
     /// Check a resulting account after executing the instruction.
     ResultingAccount(AccountCheck<'a>),
-    /// Check that all accounts are rent exempt
+    /// Check that all accounts are rent exempt.
     AllRentExempt,
+    /// Custom check for accounts.
+    Custom((Box<AccountCheckFn>, &'static str)),
 }
 
 pub struct Check<'a> {
@@ -75,10 +79,18 @@ impl<'a> Check<'a> {
         AccountCheckBuilder::new(pubkey)
     }
 
-    /// Check that all resulting accounts are rent exempt
+    /// Check that all resulting accounts are rent exempt.
     pub fn all_rent_exempt() -> Self {
         Check::new(CheckType::AllRentExempt)
     }
+
+    /// Custom check for accounts.
+    pub fn custom<F>(function: F, function_name: &'static str) -> Self
+    where
+        F: Fn(&[(Pubkey, Account)]) -> bool + 'static,
+    {
+        Check::new(CheckType::Custom((Box::new(function), function_name)))
+    }
 }
 
 enum AccountStateCheck {
@@ -298,6 +310,10 @@ impl InstructionResult {
                         }
                     }
                 }
+                CheckType::Custom((function, function_name)) => {
+                    println!("Calling {}", *function_name);
+                    pass &= function(&self.resulting_accounts);
+                }
             }
         }
         pass