test: add test for custom type decoding

crates/forge/tests/cli/test_cmd.rs

@@ -368,6 +368,7 @@ forgetest_init!(exit_code_error_on_fail_fast_with_json, |prj, cmd| {
     cmd.assert_err();
 });
 
+// <https://github.com/foundry-rs/foundry/issues/6531>
 forgetest_init!(repro_6531, |prj, cmd| {
     prj.wipe_contracts();
 
@@ -401,3 +402,33 @@ contract USDCCallingTest is Test {
 
     cmd.args(["test", "-vvvv"]).unchecked_output().stdout_matches_content(&expected);
 });
+
+// <https://github.com/foundry-rs/foundry/issues/6579>
+forgetest_init!(include_custom_types_in_traces, |prj, cmd| {
+    prj.wipe_contracts();
+
+    prj.add_test(
+        "Contract.t.sol",
+        r#"
+import {Test} from "forge-std/Test.sol";
+
+error PoolNotInitialized();
+event MyEvent(uint256 a);
+
+contract CustomTypesTest is Test {
+    function testErr() public pure {
+       revert PoolNotInitialized();
+    }
+    function testEvent() public {
+       emit MyEvent(100);
+    }
+}
+   "#,
+    )
+    .unwrap();
+
+    cmd.args(["test", "-vvvv"]).unchecked_output().stdout_matches_path(
+        PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+            .join("tests/fixtures/include_custom_types_in_traces.stdout"),
+    );
+});

crates/forge/tests/fixtures/include_custom_types_in_traces.stdout

@@ -0,0 +1,25 @@
+Compiling 1 files with 0.8.23
+Solc 0.8.23 finished in 798.51ms
+Compiler run successful!
+
+Running 2 tests for test/Contract.t.sol:CustomTypesTest
+[FAIL. Reason: PoolNotInitialized()] testErr() (gas: 231)
+Traces:
+  [231] CustomTypesTest::testErr()
+    └─ ← PoolNotInitialized()
+
+[PASS] testEvent() (gas: 1312)
+Traces:
+  [1312] CustomTypesTest::testEvent()
+    ├─ emit MyEvent(a: 100)
+    └─ ← ()
+
+Test result: FAILED. 1 passed; 1 failed; 0 skipped; finished in 3.88ms
+
+Ran 1 test suites: 1 tests passed, 1 failed, 0 skipped (2 total tests)
+
+Failing tests:
+Encountered 1 failing test in test/Contract.t.sol:CustomTypesTest
+[FAIL. Reason: PoolNotInitialized()] testErr() (gas: 231)
+
+Encountered a total of 1 failing tests, 1 tests succeeded