filtering/rulelist: imp docs, tests

internal/filtering/rulelist/filter.go

@@ -47,8 +47,8 @@ type Filter struct {
 	// rulesCount contains the number of rules in this rule-list filter.
 	rulesCount int
 
-	// checksum is a CRC32 hash used to quickly check if the rule-list filter's
-	// contents have changed.
+	// checksum is a CRC32 hash used to quickly check if the rules within a list
+	// file have changed.
 	checksum uint32
 
 	// enabled, if true, means that this rule-list filter is used for filtering.

internal/filtering/rulelist/filter_test.go

@@ -25,8 +25,8 @@ func TestFilter_Refresh(t *testing.T) {
 		testRuleTextTitle +
 			testRuleTextBlocked,
 	)
-	urlParseErr := os.WriteFile(initialFile, initialData, 0o644)
-	require.NoError(t, urlParseErr)
+	writeErr := os.WriteFile(initialFile, initialData, 0o644)
+	require.NoError(t, writeErr)
 
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		pt := testutil.PanicT{}
@@ -35,8 +35,8 @@ func TestFilter_Refresh(t *testing.T) {
 		require.NoError(pt, err)
 	}))
 
-	srvURL, urlParseErr := url.Parse(srv.URL)
-	require.NoError(t, urlParseErr)
+	srvURL, urlErr := url.Parse(srv.URL)
+	require.NoError(t, urlErr)
 
 	testCases := []struct {
 		url           *url.URL
@@ -74,11 +74,14 @@ func TestFilter_Refresh(t *testing.T) {
 				URLFilterID: testURLFilterID,
 				Enabled:     true,
 			})
-			testutil.AssertErrorMsg(t, tc.wantNewErrMsg, err)
 			if tc.wantNewErrMsg != "" {
+				assert.EqualError(t, err, tc.wantNewErrMsg)
+
 				return
 			}
 
+			testutil.CleanupAndRequireSuccess(t, f.Close)
+
 			require.NotNil(t, f)
 
 			ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
@@ -99,9 +102,6 @@ func TestFilter_Refresh(t *testing.T) {
 			// Check that the cached file exists.
 			_, err = os.Stat(filepath.Join(cacheDir, uid.String()+".txt"))
 			require.NoError(t, err)
-
-			err = f.Close()
-			require.NoError(t, err)
 		})
 	}
 }

internal/filtering/rulelist/rulelist.go

@@ -13,6 +13,9 @@ import (
 
 // DefaultRuleBufSize is the default length of a buffer used to read a line with
 // a filtering rule, in bytes.
+//
+// TODO(a.garipov): Consider using [datasize.ByteSize].  It is currently only
+// used as an int.
 const DefaultRuleBufSize = 1024
 
 // DefaultMaxRuleListSize is the default maximum filtering-rule list size.
@@ -25,7 +28,7 @@ type URLFilterID = int
 // UID is the type for the unique IDs of filtering-rule lists.
 type UID uuid.UUID
 
-// NewUID returns a new filtering-rule list UID. Any error returned is an error
+// NewUID returns a new filtering-rule list UID.  Any error returned is an error
 // from the cryptographic randomness reader.
 func NewUID() (uid UID, err error) {
 	uuidv7, err := uuid.NewV7()