diff --git a/metropolis/pkg/logtree/klog_test.go b/metropolis/pkg/logtree/klog_test.go
new file mode 100644
index 0000000..f163f16
--- /dev/null
+++ b/metropolis/pkg/logtree/klog_test.go
@@ -0,0 +1,82 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logtree
+
+import (
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestParse(t *testing.T) {
+	// Injected 'now'. Used to make these tests reproducible and to allow for
+	// testing the log-across-year edgecase.
+	// Fri 12 Mar 2021 03:46:26 PM UTC
+	now := time.Unix(1615563986, 123456789)
+	// Sat 01 Jan 2000 12:00:01 AM UTC
+	nowNewYear := time.Unix(946684801, 0)
+
+	for i, te := range []struct{
+		now time.Time
+		line string
+		want *LeveledPayload
+	}{
+		// 0: Simple case: everything should parse correctly.
+		{ now, "E0312 14:20:04.240540    204 shared_informer.go:247] Caches are synced for attach detach", &LeveledPayload{
+			messages: []string{"Caches are synced for attach detach"},
+			timestamp: time.Date(2021, 03, 12, 14, 20, 4, 240540000, time.UTC),
+			severity: ERROR,
+			file: "shared_informer.go",
+			line: 247,
+		} },
+		// 1: Mumbling line, should fail.
+		{ now, "Application starting up...", nil},
+		// 2: Empty line, should fail.
+		{ now, "", nil},
+		// 3: Line from the future, should fail.
+		{ now, "I1224 14:20:04.240540    204 john_titor.go:247] I'm sorry, what day is it today? Uuuh, and what year?", nil },
+		// 4: Log-across-year edge case. The log was emitted right before a year
+		//    rollover, and parsed right after it. It should be attributed to the
+		//    previous year.
+		{ nowNewYear, "I1231 23:59:43.123456    123 fry.go:123] Here's to another lousy millenium!", &LeveledPayload{
+			messages: []string{"Here's to another lousy millenium!"},
+			timestamp: time.Date(1999, 12, 31, 23, 59, 43, 123456000, time.UTC),
+			severity: INFO,
+			file: "fry.go",
+			line: 123,
+		}},
+		// 5: Invalid severity, should fail.
+		{ now, "D0312 14:20:04.240540    204 shared_informer.go:247] Caches are synced for attach detach", nil },
+		// 6: Invalid time, should fail.
+		{ now, "D0312 25:20:04.240540    204 shared_informer.go:247] Caches are synced for attach detach", nil },
+		// 7: Simple case without sub-second timing: everything should parse correctly
+		{ now, "E0312 14:20:04 204 shared_informer.go:247] Caches are synced for attach detach", &LeveledPayload{
+			messages: []string{"Caches are synced for attach detach"},
+			timestamp: time.Date(2021, 03, 12, 14, 20, 4, 0, time.UTC),
+			severity: ERROR,
+			file: "shared_informer.go",
+			line: 247,
+		} },
+	} {
+		got := parse(te.now, te.line)
+		if diff := cmp.Diff(te.want, got, cmp.AllowUnexported(LeveledPayload{})); diff != "" {
+			t.Errorf("%d: mismatch (-want +got):\n%s", i, diff)
+		}
+	}
+}
+