tests: apply should_ignore beforehand in purge_caches tests

Author: pietroalbini

tests/integration/purge_caches.rs

@@ -49,24 +49,24 @@ fn test_purge_caches() -> Result<(), Error> {
 
 /// Define which files should be ignored when comparing the two workspaces. If there are expected
 /// changes, update the function to match them.
-fn should_ignore(base: &Path, path: &Path) -> bool {
+fn should_compare(base: &Path, path: &Path) -> bool {
     let components = match path.strip_prefix(base) {
         Ok(stripped) => stripped
             .components()
             .map(|component| component.as_os_str().to_string_lossy().to_string())
             .collect::<Vec<_>>(),
-        Err(_) => return false,
+        Err(_) => return true,
     };
 
     let components = components.iter().map(|c| c.as_str()).collect::<Vec<_>>();
     match components.as_slice() {
         // The indexes could be updated during the build. The index is not considered a cache
         // though, so it's fine to ignore it during the comparison.
-        ["cargo-home", "registry", "index", _, ".git", ..] => true,
-        ["cargo-home", "registry", "index", _, ".cargo-index-lock"] => true,
-        ["cargo-home", "registry", "index", _, ".last-updated"] => true,
+        ["cargo-home", "registry", "index", _, ".git", ..] => false,
+        ["cargo-home", "registry", "index", _, ".cargo-index-lock"] => false,
+        ["cargo-home", "registry", "index", _, ".last-updated"] => false,
 
-        _ => false,
+        _ => true,
     }
 }
 
@@ -80,7 +80,10 @@ impl WorkspaceContents {
     fn collect(path: &Path) -> Result<Self, Error> {
         let mut files = HashMap::new();
 
-        for entry in walkdir::WalkDir::new(path) {
+        for entry in walkdir::WalkDir::new(path)
+            .into_iter()
+            .filter_entry(|entry| should_compare(path, entry.path()))
+        {
             let entry = entry?;
             let metadata = entry.metadata()?;
 
@@ -103,10 +106,6 @@ impl WorkspaceContents {
         println!("=== start directory differences ===");
 
         for (path, start_digest) in self.files.into_iter() {
-            if should_ignore(&self.base, &path) {
-                continue;
-            }
-
             if let Some(end_digest) = other.files.remove(&path) {
                 if start_digest != end_digest {
                     println!("file {} changed its size", path.display());
@@ -119,10 +118,6 @@ impl WorkspaceContents {
         }
 
         for (path, _) in other.files.into_iter() {
-            if should_ignore(&other.base, &path) {
-                continue;
-            }
-
             println!("file {} was added", path.display());
             same = false;
         }