diff --git a/tests/functional/lang.sh b/tests/functional/lang.sh
index 8310ac1f6..cac0b896d 100755
--- a/tests/functional/lang.sh
+++ b/tests/functional/lang.sh
@@ -25,7 +25,6 @@ nix-instantiate --eval -E 'builtins.addErrorContext "Hello" 123' 2>&1
 nix-instantiate --trace-verbose --eval -E 'builtins.traceVerbose "Hello" 123' 2>&1 | grepQuiet Hello
 nix-instantiate --eval -E 'builtins.traceVerbose "Hello" 123' 2>&1 | grepQuietInverse Hello
 nix-instantiate --show-trace --eval -E 'builtins.addErrorContext "Hello" 123' 2>&1 | grepQuietInverse Hello
-expectStderr 1 nix-instantiate --show-trace --eval -E 'builtins.addErrorContext "Hello" (throw "Foo")' | grepQuiet Hello
 expectStderr 1 nix-instantiate --show-trace --eval -E 'builtins.addErrorContext "Hello %" (throw "Foo")' | grepQuiet 'Hello %'
 
 nix-instantiate --eval -E 'let x = builtins.trace { x = x; } true; in x' \
diff --git a/tests/functional/lang/eval-okay-nul.flags b/tests/functional/lang/eval-okay-nul.flags
deleted file mode 100644
index 33da0f779..000000000
--- a/tests/functional/lang/eval-okay-nul.flags
+++ /dev/null
@@ -1 +0,0 @@
---extra-deprecated-features nul-bytes
diff --git a/tests/functional/lang/eval-okay-nul.out.exp b/tests/functional/lang/eval-okay-nul.out.exp
deleted file mode 100644
index 257cc5642..000000000
--- a/tests/functional/lang/eval-okay-nul.out.exp
+++ /dev/null
@@ -1 +0,0 @@
-foo
diff --git a/tests/functional/lang/parse-fail-crlf.nix b/tests/functional/lang/parse-fail-crlf.nix
deleted file mode 120000
index bcf59ab82..000000000
--- a/tests/functional/lang/parse-fail-crlf.nix
+++ /dev/null
@@ -1 +0,0 @@
-parse-okay-crlf.nix
\ No newline at end of file
diff --git a/tests/functional/lang/parse-fail-nul.nix b/tests/functional/lang/parse-fail-nul.nix
deleted file mode 120000
index 9b0527d33..000000000
--- a/tests/functional/lang/parse-fail-nul.nix
+++ /dev/null
@@ -1 +0,0 @@
-eval-okay-nul.nix
\ No newline at end of file
diff --git a/tests/functional/lang/parse-okay-crlf.flags b/tests/functional/lang/parse-okay-crlf.flags
deleted file mode 100644
index a7c7a5cbe..000000000
--- a/tests/functional/lang/parse-okay-crlf.flags
+++ /dev/null
@@ -1 +0,0 @@
---extra-deprecated-features cr-line-endings
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp b/tests/functional2/lang/bad_string_interpolation/eval-fail-1.err.exp
similarity index 60%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp
rename to tests/functional2/lang/bad_string_interpolation/eval-fail-1.err.exp
index 7c144c7e2..a9728e8bb 100644
--- a/tests/functional/lang/eval-fail-bad-string-interpolation-1.err.exp
+++ b/tests/functional2/lang/bad_string_interpolation/eval-fail-1.err.exp
@@ -1,8 +1,8 @@
 error:
        … while evaluating a path segment
-         at /pwd/eval-fail-bad-string-interpolation-1.nix:1:2:
+         at /pwd/in.nix:1:2:
             1| "${x: x}"
              |  ^
             2|
 
-       error: cannot coerce a function to a string: «lambda @ /pwd/eval-fail-bad-string-interpolation-1.nix:1:4»
+       error: cannot coerce a function to a string: «lambda @ /pwd/in.nix:1:4»
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-2.err.exp b/tests/functional2/lang/bad_string_interpolation/eval-fail-2.err.exp
similarity index 100%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-2.err.exp
rename to tests/functional2/lang/bad_string_interpolation/eval-fail-2.err.exp
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp b/tests/functional2/lang/bad_string_interpolation/eval-fail-3.err.exp
similarity index 60%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp
rename to tests/functional2/lang/bad_string_interpolation/eval-fail-3.err.exp
index ef79ad2ad..3a1e06e2e 100644
--- a/tests/functional/lang/eval-fail-bad-string-interpolation-3.err.exp
+++ b/tests/functional2/lang/bad_string_interpolation/eval-fail-3.err.exp
@@ -1,8 +1,8 @@
 error:
        … while evaluating a path segment
-         at /pwd/eval-fail-bad-string-interpolation-3.nix:1:3:
+         at /pwd/in.nix:1:3:
             1| ''${x: x}''
              |   ^
             2|
 
-       error: cannot coerce a function to a string: «lambda @ /pwd/eval-fail-bad-string-interpolation-3.nix:1:5»
+       error: cannot coerce a function to a string: «lambda @ /pwd/in.nix:1:5»
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp b/tests/functional2/lang/bad_string_interpolation/eval-fail-4.err.exp
similarity index 86%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp
rename to tests/functional2/lang/bad_string_interpolation/eval-fail-4.err.exp
index bd4dc48ee..555bc7e70 100644
--- a/tests/functional/lang/eval-fail-bad-string-interpolation-4.err.exp
+++ b/tests/functional2/lang/bad_string_interpolation/eval-fail-4.err.exp
@@ -1,6 +1,6 @@
 error:
        … while evaluating a path segment
-         at /pwd/eval-fail-bad-string-interpolation-4.nix:9:3:
+         at /pwd/in.nix:9:3:
             8| # The error message should not be too long.
             9| ''${pkgs}''
              |   ^
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-1.nix b/tests/functional2/lang/bad_string_interpolation/in-1.nix
similarity index 100%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-1.nix
rename to tests/functional2/lang/bad_string_interpolation/in-1.nix
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-2.nix b/tests/functional2/lang/bad_string_interpolation/in-2.nix
similarity index 100%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-2.nix
rename to tests/functional2/lang/bad_string_interpolation/in-2.nix
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-3.nix b/tests/functional2/lang/bad_string_interpolation/in-3.nix
similarity index 100%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-3.nix
rename to tests/functional2/lang/bad_string_interpolation/in-3.nix
diff --git a/tests/functional/lang/eval-fail-bad-string-interpolation-4.nix b/tests/functional2/lang/bad_string_interpolation/in-4.nix
similarity index 100%
rename from tests/functional/lang/eval-fail-bad-string-interpolation-4.nix
rename to tests/functional2/lang/bad_string_interpolation/in-4.nix
diff --git a/tests/functional2/lang/err_context/__init__.py b/tests/functional2/lang/err_context/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/functional2/lang/err_context/test_err_context.py b/tests/functional2/lang/err_context/test_err_context.py
new file mode 100644
index 000000000..380b8b09d
--- /dev/null
+++ b/tests/functional2/lang/err_context/test_err_context.py
@@ -0,0 +1,10 @@
+from functional2.testlib.fixtures.nix import Nix
+
+
+def test_err_context(nix: Nix):
+    # the lang test framework doesn't check this folder, as there is a custom test in here
+    # it won't scream about missing an `in.nix` or .exp files
+    result = nix.nix_instantiate(
+        ["--show-trace", "--eval", "-E", 'builtins.addErrorContext "Hello" (throw "Foo")']
+    ).run()
+    assert "Hello" in result.expect(1).stderr_s
diff --git a/tests/functional/lang/eval-okay-import.exp b/tests/functional2/lang/import/eval-okay.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-import.exp
rename to tests/functional2/lang/import/eval-okay.out.exp
diff --git a/tests/functional/lang/imported.nix b/tests/functional2/lang/import/imported.nix
similarity index 100%
rename from tests/functional/lang/imported.nix
rename to tests/functional2/lang/import/imported.nix
diff --git a/tests/functional/lang/imported2.nix b/tests/functional2/lang/import/imported2.nix
similarity index 100%
rename from tests/functional/lang/imported2.nix
rename to tests/functional2/lang/import/imported2.nix
diff --git a/tests/functional/lang/eval-okay-import.nix b/tests/functional2/lang/import/in.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-import.nix
rename to tests/functional2/lang/import/in.nix
diff --git a/tests/functional2/lang/import/test.toml b/tests/functional2/lang/import/test.toml
new file mode 100644
index 000000000..4c9e923e2
--- /dev/null
+++ b/tests/functional2/lang/import/test.toml
@@ -0,0 +1,3 @@
+[eval-okay]
+runner = "eval-okay"
+extra-files = ["imported.nix", "imported2.nix"]
diff --git a/tests/functional/lang/parse-okay-crlf.exp b/tests/functional2/lang/line_endings/allow-depr.out.exp
similarity index 100%
rename from tests/functional/lang/parse-okay-crlf.exp
rename to tests/functional2/lang/line_endings/allow-depr.out.exp
diff --git a/tests/functional/lang/parse-fail-crlf.err.exp b/tests/functional2/lang/line_endings/depr.err.exp
similarity index 88%
rename from tests/functional/lang/parse-fail-crlf.err.exp
rename to tests/functional2/lang/line_endings/depr.err.exp
index 06c375774..f6ca6b19a 100644
--- a/tests/functional/lang/parse-fail-crlf.err.exp
+++ b/tests/functional2/lang/line_endings/depr.err.exp
@@ -1,11 +1,11 @@
 warning: CR (`\r`) and CRLF (`\r\n`) line endings are not supported. Please inspect the file and normalize it to use LF (`\n`) line endings instead. Use --extra-deprecated-features cr-line-endings to silence this warning.
-         at /pwd/parse-okay-crlf.nix:7:21:
+         at /pwd/in.nix:7:21:
               6|   x =
               7|   # Dit is een test.
                |                     ^
               8| y;
 error: CR (`\r`) and CRLF (`\r\n`) line endings are not supported. Please inspect the file and normalize it to use LF (`\n`) line endings instead. Use --extra-deprecated-features cr-line-endings to silence this warning.
-       at /pwd/parse-okay-crlf.nix:14:15:
+       at /pwd/in.nix:14:15:
            13|   # translated to LF.
            14|   foo = "multi
              |               ^
diff --git a/tests/functional/lang/parse-okay-crlf.nix b/tests/functional2/lang/line_endings/in.nix
similarity index 100%
rename from tests/functional/lang/parse-okay-crlf.nix
rename to tests/functional2/lang/line_endings/in.nix
diff --git a/tests/functional2/lang/line_endings/test.toml b/tests/functional2/lang/line_endings/test.toml
new file mode 100644
index 000000000..beff445a7
--- /dev/null
+++ b/tests/functional2/lang/line_endings/test.toml
@@ -0,0 +1,6 @@
+[depr]
+runner = "parse-fail"
+
+[allow-depr]
+runner = "parse-okay"
+flags = ["--extra-deprecated-features", "cr-line-endings"]
diff --git a/tests/functional/lang/eval-okay-nul.exp b/tests/functional2/lang/nul_bytes/eval-allow-depr.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-nul.exp
rename to tests/functional2/lang/nul_bytes/eval-allow-depr.out.exp
diff --git a/tests/functional/lang/parse-fail-nul.err.exp b/tests/functional2/lang/nul_bytes/eval-depr.err.exp
similarity index 87%
rename from tests/functional/lang/parse-fail-nul.err.exp
rename to tests/functional2/lang/nul_bytes/eval-depr.err.exp
index b0f3eb3b8..3512163d0 100644
Binary files a/tests/functional/lang/parse-fail-nul.err.exp and b/tests/functional2/lang/nul_bytes/eval-depr.err.exp differ
diff --git a/tests/functional/lang/eval-okay-nul.nix b/tests/functional2/lang/nul_bytes/in.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-nul.nix
rename to tests/functional2/lang/nul_bytes/in.nix
diff --git a/tests/functional2/lang/nul_bytes/parse-allow-depr.out.exp b/tests/functional2/lang/nul_bytes/parse-allow-depr.out.exp
new file mode 100644
index 000000000..9b92fcc9a
--- /dev/null
+++ b/tests/functional2/lang/nul_bytes/parse-allow-depr.out.exp
@@ -0,0 +1,3 @@
+_type: ExprLiteral
+value: foo
+valueType: String
diff --git a/tests/functional2/lang/nul_bytes/parse-depr.err.exp b/tests/functional2/lang/nul_bytes/parse-depr.err.exp
new file mode 100644
index 000000000..3512163d0
Binary files /dev/null and b/tests/functional2/lang/nul_bytes/parse-depr.err.exp differ
diff --git a/tests/functional2/lang/nul_bytes/test.toml b/tests/functional2/lang/nul_bytes/test.toml
new file mode 100644
index 000000000..772fbd8f2
--- /dev/null
+++ b/tests/functional2/lang/nul_bytes/test.toml
@@ -0,0 +1,13 @@
+[eval-depr]
+runner = "eval-fail"
+
+[eval-allow-depr]
+runner = "eval-okay"
+flags = ["--extra-deprecated-features", "nul-bytes"]
+
+[parse-depr]
+runner = "parse-fail"
+
+[parse-allow-depr]
+runner = "parse-okay"
+flags = ["--extra-deprecated-features", "nul-bytes"]
diff --git a/tests/functional/lang/eval-fail-scope-5.err.exp b/tests/functional2/lang/scope/eval-fail-5.err.exp
similarity index 75%
rename from tests/functional/lang/eval-fail-scope-5.err.exp
rename to tests/functional2/lang/scope/eval-fail-5.err.exp
index 0eb2a692e..af0632055 100644
--- a/tests/functional/lang/eval-fail-scope-5.err.exp
+++ b/tests/functional2/lang/scope/eval-fail-5.err.exp
@@ -1,34 +1,34 @@
 error:
        … from call site
-         at /pwd/eval-fail-scope-5.nix:7:3:
+         at /pwd/in.nix:7:3:
             6| in
             7|   f {}
              |   ^
             8|
 
        … while calling 'f'
-         at /pwd/eval-fail-scope-5.nix:5:7:
+         at /pwd/in.nix:5:7:
             4|
             5|   f = {x ? y, y ? x}: x + y;
              |       ^
             6| in
 
        … while evaluating x
-         at /pwd/eval-fail-scope-5.nix:5:23:
+         at /pwd/in.nix:5:23:
             4|
             5|   f = {x ? y, y ? x}: x + y;
              |                       ^
             6| in
 
        … while evaluating y
-         at /pwd/eval-fail-scope-5.nix:5:12:
+         at /pwd/in.nix:5:12:
             4|
             5|   f = {x ? y, y ? x}: x + y;
              |            ^
             6| in
 
        error: infinite recursion encountered
-       at /pwd/eval-fail-scope-5.nix:5:12:
+       at /pwd/in.nix:5:12:
             4|
             5|   f = {x ? y, y ? x}: x + y;
              |            ^
diff --git a/tests/functional/lang/eval-okay-scope-1.exp b/tests/functional2/lang/scope/eval-okay-1.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-1.exp
rename to tests/functional2/lang/scope/eval-okay-1.out.exp
diff --git a/tests/functional/lang/eval-okay-scope-2.exp b/tests/functional2/lang/scope/eval-okay-2.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-2.exp
rename to tests/functional2/lang/scope/eval-okay-2.out.exp
diff --git a/tests/functional/lang/eval-okay-scope-3.exp b/tests/functional2/lang/scope/eval-okay-3.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-3.exp
rename to tests/functional2/lang/scope/eval-okay-3.out.exp
diff --git a/tests/functional/lang/eval-okay-scope-4.exp b/tests/functional2/lang/scope/eval-okay-4.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-4.exp
rename to tests/functional2/lang/scope/eval-okay-4.out.exp
diff --git a/tests/functional/lang/eval-okay-scope-6.exp b/tests/functional2/lang/scope/eval-okay-6.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-6.exp
rename to tests/functional2/lang/scope/eval-okay-6.out.exp
diff --git a/tests/functional/lang/eval-okay-scope-7.exp b/tests/functional2/lang/scope/eval-okay-7.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-7.exp
rename to tests/functional2/lang/scope/eval-okay-7.out.exp
diff --git a/tests/functional/lang/eval-okay-scope-1.nix b/tests/functional2/lang/scope/in-1.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-1.nix
rename to tests/functional2/lang/scope/in-1.nix
diff --git a/tests/functional/lang/eval-okay-scope-2.nix b/tests/functional2/lang/scope/in-2.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-2.nix
rename to tests/functional2/lang/scope/in-2.nix
diff --git a/tests/functional/lang/eval-okay-scope-3.nix b/tests/functional2/lang/scope/in-3.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-3.nix
rename to tests/functional2/lang/scope/in-3.nix
diff --git a/tests/functional/lang/eval-okay-scope-4.nix b/tests/functional2/lang/scope/in-4.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-4.nix
rename to tests/functional2/lang/scope/in-4.nix
diff --git a/tests/functional/lang/eval-fail-scope-5.nix b/tests/functional2/lang/scope/in-5.nix
similarity index 100%
rename from tests/functional/lang/eval-fail-scope-5.nix
rename to tests/functional2/lang/scope/in-5.nix
diff --git a/tests/functional/lang/eval-okay-scope-6.nix b/tests/functional2/lang/scope/in-6.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-6.nix
rename to tests/functional2/lang/scope/in-6.nix
diff --git a/tests/functional/lang/eval-okay-scope-7.nix b/tests/functional2/lang/scope/in-7.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-scope-7.nix
rename to tests/functional2/lang/scope/in-7.nix
diff --git a/tests/functional/lang/eval-okay-with.exp b/tests/functional2/lang/with/eval-okay.out.exp
similarity index 100%
rename from tests/functional/lang/eval-okay-with.exp
rename to tests/functional2/lang/with/eval-okay.out.exp
diff --git a/tests/functional/lang/eval-okay-with.nix b/tests/functional2/lang/with/in.nix
similarity index 100%
rename from tests/functional/lang/eval-okay-with.nix
rename to tests/functional2/lang/with/in.nix