Add build test and remove layout overwrite

.chloggen/fix-file-sort-layout-overwrite.yaml

@@ -0,0 +1,20 @@
+# Use this changelog template to create an entry for release notes.
+# If your change doesn't affect end users, such as a test fix or a tooling change,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: "bug_fix"
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: filelogreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix file sort timestamp layout being overwritten
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [24041]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

pkg/stanza/fileconsumer/file_sort.go

@@ -94,11 +94,10 @@ func (f *TimestampSortRule) validate() error {
 		f.Location = "UTC"
 	}
 
-	layout, err := strptime.ToNative(f.Layout)
+	_, err := strptime.ToNative(f.Layout)
 	if err != nil {
 		return errors.Wrap(err, "parse strptime layout")
 	}
-	f.Layout = layout
 
 	return nil
 }

pkg/stanza/fileconsumer/file_test.go

@@ -705,6 +705,42 @@ func TestMultiFileSort(t *testing.T) {
 	expectNoTokens(t, emitCalls)
 }
 
+func TestMultiFileSortTimestamp(t *testing.T) {
+	t.Parallel()
+
+	tempDir := t.TempDir()
+	cfg := NewConfig().includeDir(tempDir)
+	cfg.StartAt = "beginning"
+	cfg.MatchingCriteria.OrderingCriteria.Regex = `.*(?P<value>\d).log`
+	cfg.MatchingCriteria.OrderingCriteria.SortBy = []SortRuleImpl{
+		{
+			&TimestampSortRule{
+				BaseSortRule: BaseSortRule{
+					RegexKey: `value`,
+					SortType: "timestamp",
+				},
+				Layout: "%Y%m%d%H",
+			},
+		},
+	}
+
+	operator, emitCalls := buildTestManager(t, cfg)
+
+	temp1 := openTempWithPattern(t, tempDir, ".*2023020602.log")
+	temp2 := openTempWithPattern(t, tempDir, ".*2023020603.log")
+
+	writeString(t, temp1, "testlog1\n")
+	writeString(t, temp2, "testlog2\n")
+
+	require.NoError(t, operator.Start(testutil.NewMockPersister("test")))
+	defer func() {
+		require.NoError(t, operator.Stop())
+	}()
+
+	waitForTokens(t, emitCalls, [][]byte{[]byte("testlog2")})
+	expectNoTokens(t, emitCalls)
+}
+
 func TestMultiFileParallel_PreloadedFiles(t *testing.T) {
 	t.Parallel()