Add a test for CompoundLens.

Author: nedtwigg

python/selfie-lib/tests/CompoundLens_test.py

@@ -0,0 +1,41 @@
+from selfie_lib import CompoundLens, Snapshot
+
+
+def test_replace_all():
+    replace_all = CompoundLens().replace_all("e", "E")
+    assert (
+        repr(replace_all(Snapshot.of("subject").plus_facet("key", "value")))
+        == """Snapshot.of('subjEct')
+  .plus_facet('key', 'valuE')"""
+    )
+
+
+def test_replace_all_regex():
+    replace_all_regex = CompoundLens().replace_all_regex(r"(\w+)", r"\1!")
+    assert (
+        repr(
+            replace_all_regex(
+                Snapshot.of("this is subject").plus_facet("key", "this is facet")
+            )
+        )
+        == """Snapshot.of('this! is! subject!')
+  .plus_facet('key', 'this! is! facet!')"""
+    )
+
+
+def test_set_facet_from():
+    set_facet_from = CompoundLens().set_facet_from("uppercase", "", lambda s: s.upper())
+    assert (
+        repr(set_facet_from(Snapshot.of("subject")))
+        == """Snapshot.of('subject')
+  .plus_facet('uppercase', 'SUBJECT')"""
+    )
+
+
+def test_mutate_facet():
+    mutate_facet = CompoundLens().mutate_facet("key", lambda s: s.upper())
+    assert (
+        repr(mutate_facet(Snapshot.of("subject").plus_facet("key", "facet")))
+        == """Snapshot.of('subject')
+  .plus_facet('key', 'FACET')"""
+    )