diff --git a/tests/functional/lang/eval-okay-equal-function-attrset-distinct-similar.exp b/tests/functional/lang/eval-okay-equal-function-attrset-distinct-similar.exp
new file mode 100644
index 000000000..c508d5366
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-attrset-distinct-similar.exp
@@ -0,0 +1 @@
+false
diff --git a/tests/functional/lang/eval-okay-equal-function-attrset-distinct-similar.nix b/tests/functional/lang/eval-okay-equal-function-attrset-distinct-similar.nix
new file mode 100644
index 000000000..13c30d9f7
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-attrset-distinct-similar.nix
@@ -0,0 +1,3 @@
+# Distinct but not identical functions in attribute set compare as unequal
+# See https://nix.dev/manual/nix/latest/language/operators#equality
+{ a = (x: x); } == { a = (x: x); }
diff --git a/tests/functional/lang/eval-okay-equal-function-attrset-identical.exp b/tests/functional/lang/eval-okay-equal-function-attrset-identical.exp
new file mode 100644
index 000000000..27ba77dda
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-attrset-identical.exp
@@ -0,0 +1 @@
+true
diff --git a/tests/functional/lang/eval-okay-equal-function-attrset-identical.nix b/tests/functional/lang/eval-okay-equal-function-attrset-identical.nix
new file mode 100644
index 000000000..830267c82
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-attrset-identical.nix
@@ -0,0 +1,10 @@
+# Function comparison in attribute set uses value identity optimization
+# See https://nix.dev/manual/nix/latest/language/operators#value-identity-optimization
+let
+  f = x: x;
+in
+{
+  a = f;
+} == {
+  a = f;
+}
diff --git a/tests/functional/lang/eval-okay-equal-function-direct-distinct-similar.exp b/tests/functional/lang/eval-okay-equal-function-direct-distinct-similar.exp
new file mode 100644
index 000000000..c508d5366
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-direct-distinct-similar.exp
@@ -0,0 +1 @@
+false
diff --git a/tests/functional/lang/eval-okay-equal-function-direct-distinct-similar.nix b/tests/functional/lang/eval-okay-equal-function-direct-distinct-similar.nix
new file mode 100644
index 000000000..f3a931c6b
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-direct-distinct-similar.nix
@@ -0,0 +1,3 @@
+# Direct comparison of distinct but not identical functions returns false
+# See https://nix.dev/manual/nix/latest/language/operators#equality
+(x: x) == (x: x)
diff --git a/tests/functional/lang/eval-okay-equal-function-direct-identical.exp b/tests/functional/lang/eval-okay-equal-function-direct-identical.exp
new file mode 100644
index 000000000..c508d5366
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-direct-identical.exp
@@ -0,0 +1 @@
+false
diff --git a/tests/functional/lang/eval-okay-equal-function-direct-identical.nix b/tests/functional/lang/eval-okay-equal-function-direct-identical.nix
new file mode 100644
index 000000000..f91a39fb8
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-direct-identical.nix
@@ -0,0 +1,6 @@
+# Direct comparison of identical function returns false
+# See https://nix.dev/manual/nix/latest/language/operators#equality
+let
+  f = x: x;
+in
+f == f
diff --git a/tests/functional/lang/eval-okay-equal-function-list-distinct-similar.exp b/tests/functional/lang/eval-okay-equal-function-list-distinct-similar.exp
new file mode 100644
index 000000000..c508d5366
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-list-distinct-similar.exp
@@ -0,0 +1 @@
+false
diff --git a/tests/functional/lang/eval-okay-equal-function-list-distinct-similar.nix b/tests/functional/lang/eval-okay-equal-function-list-distinct-similar.nix
new file mode 100644
index 000000000..cd6182770
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-list-distinct-similar.nix
@@ -0,0 +1,3 @@
+# Distinct but not identical functions in list compare as unequal
+# See https://nix.dev/manual/nix/latest/language/operators#equality
+[ (x: x) ] == [ (x: x) ]
diff --git a/tests/functional/lang/eval-okay-equal-function-list-identical.exp b/tests/functional/lang/eval-okay-equal-function-list-identical.exp
new file mode 100644
index 000000000..27ba77dda
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-list-identical.exp
@@ -0,0 +1 @@
+true
diff --git a/tests/functional/lang/eval-okay-equal-function-list-identical.nix b/tests/functional/lang/eval-okay-equal-function-list-identical.nix
new file mode 100644
index 000000000..5156ffc47
--- /dev/null
+++ b/tests/functional/lang/eval-okay-equal-function-list-identical.nix
@@ -0,0 +1,6 @@
+# Function comparison in list uses value identity optimization
+# See https://nix.dev/manual/nix/latest/language/operators#value-identity-optimization
+let
+  f = x: x;
+in
+[ f ] == [ f ]