From 33141cd13394945985eb292e80b6e41eeeebc14e Mon Sep 17 00:00:00 2001
From: Sergei Zimmerman <xokdvium@proton.me>
Date: Sun, 18 May 2025 22:52:48 +0000
Subject: [PATCH] tests/functional: Add tests for flamegraph profiler

The tests are mostly based on existing `function-trace.sh`
with some tests for corner cases.
---
 tests/functional/flamegraph-profiler.sh | 91 +++++++++++++++++++++++++
 tests/functional/meson.build            |  1 +
 2 files changed, 92 insertions(+)
 create mode 100755 tests/functional/flamegraph-profiler.sh

diff --git a/tests/functional/flamegraph-profiler.sh b/tests/functional/flamegraph-profiler.sh
new file mode 100755
index 000000000..0c35037a8
--- /dev/null
+++ b/tests/functional/flamegraph-profiler.sh
@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+
+source common.sh
+
+set +x
+
+expect_trace() {
+    expr="$1"
+    expect="$2"
+    actual=$(
+        nix-instantiate \
+            --eval-profiler flamegraph \
+            --eval-profiler-frequency 0 \
+            --eval-profile-file /dev/stdout \
+            --expr "$expr" |
+            grep "«string»" || true
+    )
+
+    echo -n "Tracing expression '$expr'"
+    msg=$(
+        diff -swB \
+            <(echo "$expect") \
+            <(echo "$actual")
+    ) && result=0 || result=$?
+    if [ "$result" -eq 0 ]; then
+        echo " ok."
+    else
+        echo " failed. difference:"
+        echo "$msg"
+        return "$result"
+    fi
+}
+
+# lambda
+expect_trace 'let f = arg: arg; in f 1' "
+«string»:1:22:f 1
+"
+
+# unnamed lambda
+expect_trace '(arg: arg) 1' "
+«string»:1:1 1
+"
+
+# primop
+expect_trace 'builtins.head [0 1]' "
+«string»:1:1:primop head 1
+"
+
+# primop application
+expect_trace 'let a = builtins.all (let f = x: x; in f); in a [1]' "
+«string»:1:9:primop all 1
+«string»:1:47:primop all 1
+«string»:1:47:primop all;«string»:1:31:f 1
+"
+
+# functor
+expect_trace '{__functor = x: arg: arg;} 1' "
+«string»:1:1:functor 1
+«string»:1:1:functor;«string»:1:2 1
+"
+
+# failure inside a tryEval
+expect_trace 'builtins.tryEval (throw "example")' "
+«string»:1:1:primop tryEval 1
+«string»:1:1:primop tryEval;«string»:1:19:primop throw 1
+"
+
+# Missing argument to a formal function
+expect_trace 'let f = ({ x }: x); in f { }' "
+«string»:1:24:f 1
+"
+
+# Too many arguments to a formal function
+expect_trace 'let f = ({ x }: x); in f { x = "x"; y = "y"; }' "
+«string»:1:24:f 1
+"
+
+# Not enough arguments to a lambda
+expect_trace 'let f = (x: y: x + y); in f 1' "
+«string»:1:27:f 1
+"
+
+# Too many arguments to a lambda
+expect_trace 'let f2 = (x: x); in f2 1 2' "
+«string»:1:21:f2 1
+"
+
+# Not a function
+expect_trace '1 2' "
+«string»:1:1 1
+"
diff --git a/tests/functional/meson.build b/tests/functional/meson.build
index b2005d9d9..f5a19ac64 100644
--- a/tests/functional/meson.build
+++ b/tests/functional/meson.build
@@ -133,6 +133,7 @@ suites = [
       'post-hook.sh',
       'function-trace.sh',
       'formatter.sh',
+      'flamegraph-profiler.sh',
       'eval-store.sh',
       'why-depends.sh',
       'derivation-json.sh',