Port alias test to littlecheck

tests/checks/alias.fish

@@ -0,0 +1,18 @@
+#RUN: %fish %s
+# Avoid regressions of issue \#3860 wherein the first word of the alias ends with a semicolon
+function foo
+    echo ran foo
+end
+alias my_alias "foo; and echo foo ran"
+my_alias
+# CHECK: ran foo
+# CHECK: foo ran
+
+alias a-2='echo "hello there"'
+
+# Bare `alias` should list the aliases we have created and nothing else
+# We have to exclude two aliases because they're an artifact of the unit test
+# framework and we can't predict the definition.
+alias | grep -Ev '^alias (fish_indent|fish_key_reader) '
+# CHECK: alias a-2 'echo "hello there"'
+# CHECK: alias my_alias 'foo; and echo foo ran'