tests(f2/repl): migrate basic tests

Change-Id: I22241734a7249d376c86b3a226c5f1a82c03fd33

tests/functional2/repl_characterization/repl_basics/input.md

@@ -0,0 +1,71 @@
+---
+args: ['-v']
+---
+
+Adding variables gives simple user feedback
+
+```nix
+foo = 5
+foo = 10
+```
+```output
+Added foo.
+
+Updated foo.
+
+```
+
+Optional semicolon at the end, allow setting multiple variables in one line
+
+```nix
+foo = 2;
+foo = 2; bar = 3;
+```
+```output
+Updated foo.
+
+Updated foo.
+Added bar.
+
+```
+
+String identifiers work
+
+```nix
+"silly name" = null
+```
+```output
+Added "silly name".
+
+```
+
+Attrset syntax works, but without dynamic attrs or merging
+
+```nix
+foo.bar = "baz"
+foo
+foo."this works" = 42
+foo
+foo.bar = "baz"; foo.more = "error"
+${foo} = 10
+```
+```output
+Updated foo.
+
+{ bar = "baz"; }
+
+Updated foo.
+
+{ "this works" = 42; }
+
+error: attribute 'foo' already defined at «string»:1:18
+       at «string»:1:12:
+            1| foo.bar = "baz"; foo.more = "error"
+             |            ^
+
+error: dynamic attributes not allowed in REPL
+       at «string»:1:1:
+            1| ${foo} = 10
+             | ^
+
+```