Clean up imports, formatting and tests.

Bug: n/a
Test: atest libapkverify.test libapkverify.integration_test
Change-Id: I39686d17927741297aa3feb02ed6043ee770933b
diff --git a/apkverify/src/ziputil.rs b/apkverify/src/ziputil.rs
index bfb1c01..f18a38a 100644
--- a/apkverify/src/ziputil.rs
+++ b/apkverify/src/ziputil.rs
@@ -93,7 +93,7 @@
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::assert_contains;
+    use crate::testing::assert_contains;
     use std::io::{Cursor, Write};
     use zip::{write::FileOptions, ZipWriter};
 
@@ -125,6 +125,6 @@
         // ZipArchive::new() succeeds, but we should reject
         let res = zip_sections(Cursor::new([pre_eocd, cd, eocd].concat()));
         assert!(res.is_err());
-        assert_contains!(res.err().unwrap().to_string(), "Invalid ZIP: offset should be 0");
+        assert_contains(&res.err().unwrap().to_string(), "Invalid ZIP: offset should be 0");
     }
 }