add fish-spec

plugins/better-alias/balias.spec.fish

+import plugins/fish-spec
+import plugins/balias
+
+function describe_library -d "better-alias"
+
+  function after_all
+    functions -e changedir
+  end
+
+  function it_doesnt_fail
+    balias changedir cd
+    expect test $status --to-be-true
+  end
+
+  function it_defines_an_alias
+    functions changedir
+    expect test $status --to-be-true
+  end
+
+  function you_can_use_the_alias
+    mkdir testdir
+    changedir testdir
+    expect test $status --to-be-true
+    cd ..
+    rmdir testdir
+  end
+
+end
+
+spec.run $argv
\ No newline at end of file