1 files changed, 70 insertions, 0 deletions
diff --git a/elixir/ast_test.exs b/elixir/ast_test.exs
new file mode 100644
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+++ b/elixir/ast_test.exs
@@ -0,0 +1,70 @@
+defmodule AstTest do
+  use ExUnit.Case
+
+  test "pprint/1" do
+    assert Ast.pprint(Ast.var("x")) == "x"
+    assert Ast.pprint(Ast.abs("x", Ast.var("x"))) == "(λ x . x)"
+    assert Ast.pprint(Ast.app(Ast.var("x"), Ast.var("y"))) == "x y"
+  end
+
+  test "pprint with if expression lambda calculus" do
+    assert Ast.pprint(Ast.abs("f", Ast.abs("y", Ast.app(Ast.var("f"), Ast.var("x"))))) ==
+             "(λ f . (λ y . f x))"
+  end
+
+  test "free_vars-1" do
+    program = Ast.var("x")
+    expected = MapSet.new(["x"])
+    repr_expected = "x"
+    repr_subs_expected = "y"
+
+    assert MapSet.equal?(Ast.free_vars(program), expected)
+    assert Ast.pprint(program) == repr_expected
+
+    assert Ast.pprint(Ast.subst(program, "x", Ast.var("y"))) == repr_subs_expected
+  end
+
+  test "free_vars-2" do
+    program = Ast.abs("x", Ast.var("x"))
+    expected = MapSet.new([])
+    repr_expected = "(λ x . x)"
+    repr_subs_expected = "(λ x . x)"
+
+    assert MapSet.equal?(Ast.free_vars(program), expected)
+    assert Ast.pprint(program) == repr_expected
+
+    assert Ast.pprint(Ast.subst(program, "x", Ast.var("y"))) == repr_subs_expected
+  end
+
+  test "free_vars-3" do
+    program = Ast.app(Ast.var("f"), Ast.var("x"))
+    expected = MapSet.new(["f", "x"])
+    repr_expected = "f x"
+
+    assert MapSet.equal?(Ast.free_vars(program), expected)
+    assert Ast.pprint(program) == repr_expected
+  end
+
+  test "free_vars-4" do
+    program =
+      Ast.abs(
+        "f",
+        Ast.app(Ast.var("x"), Ast.abs("x", Ast.app(Ast.var("f"), Ast.var("x"))))
+      )
+
+    expected = MapSet.new(["x"])
+    repr_expected = "(λ f . x (λ x . f x))"
+
+    assert MapSet.equal?(Ast.free_vars(program), expected)
+    assert Ast.pprint(program) == repr_expected
+  end
+
+  test "free_vars-5" do
+    program = Ast.abs("f", Ast.abs("y", Ast.app(Ast.var("f"), Ast.var("x"))))
+    expected = MapSet.new(["x"])
+    repr_expected = "(λ f . (λ y . f x))"
+
+    assert MapSet.equal?(Ast.free_vars(program), expected)
+    assert Ast.pprint(program) == repr_expected
+  end
+end