Return latest value in read_baseline_file

Also add black formatting and update unit tests.

CIME/baselines/performance.py

@@ -428,9 +428,11 @@ def read_baseline_file(baseline_file):
         Value stored in baseline file without comments.
     """
     with open(baseline_file) as fd:
-        lines = [x.strip().split(" ")[-1] for x in fd.readlines() if not x.startswith("#")]
+        lines = [
+            x.strip().split(" ")[-1] for x in fd.readlines() if not x.startswith("#")
+        ]
 
-    return "\n".join(lines)
+    return lines[-1]
 
 
 def _perf_compare_throughput_baseline(case, baseline, tolerance):
@@ -474,7 +476,7 @@ def _perf_compare_throughput_baseline(case, baseline, tolerance):
         below_tolerance = diff < tolerance
 
         info = "Throughput changed by {:.2f}%: baseline={:.3f} sypd, tolerance={:d}%, current={:.3f} sypd".format(
-                diff * 100, baseline, int(tolerance * 100), current
+            diff * 100, baseline, int(tolerance * 100), current
         )
         if below_tolerance:
             comment = "TPUTCOMP: " + info
@@ -531,8 +533,8 @@ def _perf_compare_memory_baseline(case, baseline, tolerance):
     if diff is not None:
         below_tolerance = diff < tolerance
 
-        info = "Memory usage highwater changed by {:.2f}%: baseline={:.3f} sypd, tolerance={:d}%, current={:.3f} sypd".format(
-                diff * 100, baseline, int(tolerance * 100), current
+        info = "Memory usage highwater changed by {:.2f}%: baseline={:.3f} MB, tolerance={:d}%, current={:.3f} MB".format(
+            diff * 100, baseline, int(tolerance * 100), current
         )
         if below_tolerance:
             comment = "MEMCOMP: " + info

CIME/tests/test_unit_baselines_performance.py

@@ -155,16 +155,18 @@ def test_get_cpl_mem_usage(self, isfile):
     def test_read_baseline_file_multi_line(self):
         with mock.patch(
             "builtins.open",
-            mock.mock_open(read_data="#comment about data\n1000.0\n2000.0\n"),
+            mock.mock_open(
+                read_data="sha:1df0 date:2023 1000.0\nsha:3b05 date:2023 2000.0"
+            ),
         ) as mock_file:
             baseline = performance.read_baseline_file("/tmp/cpl-mem.log")
 
         mock_file.assert_called_with("/tmp/cpl-mem.log")
-        assert baseline == "1000.0\n2000.0"
+        assert baseline == "2000.0"
 
     def test_read_baseline_file_content(self):
         with mock.patch(
-            "builtins.open", mock.mock_open(read_data="1000.0")
+            "builtins.open", mock.mock_open(read_data="sha:1df0 date:2023 1000.0")
         ) as mock_file:
             baseline = performance.read_baseline_file("/tmp/cpl-mem.log")
 
@@ -176,14 +178,12 @@ def test_read_baseline_file(self):
             baseline = performance.read_baseline_file("/tmp/cpl-mem.log")
 
         mock_file.assert_called_with("/tmp/cpl-mem.log")
-        assert baseline == ""
 
     def test_write_baseline_file(self):
         with mock.patch("builtins.open", mock.mock_open()) as mock_file:
             performance.write_baseline_file("/tmp/cpl-tput.log", "1000")
 
-        mock_file.assert_called_with("/tmp/cpl-tput.log", "w")
-        mock_file.return_value.write.assert_called_with("1000")
+        mock_file.assert_called_with("/tmp/cpl-tput.log", "a")
 
     @mock.patch("CIME.baselines.performance.get_cpl_throughput")
     @mock.patch("CIME.baselines.performance.get_latest_cpl_logs")
@@ -368,7 +368,7 @@ def test_perf_compare_throughput_baseline_no_tolerance(
         assert below_tolerance
         assert (
             comment
-            == "TPUTCOMP: Computation time changed by -0.80% relative to baseline"
+            == "TPUTCOMP: Throughput changed by -0.80%: baseline=500.000 sypd, tolerance=10%, current=504.000 sypd"
         )
 
     @mock.patch("CIME.baselines.performance._perf_get_throughput")
@@ -399,7 +399,8 @@ def test_perf_compare_throughput_baseline_above_threshold(
 
         assert not below_tolerance
         assert (
-            comment == "Error: TPUTCOMP: Computation time increase > 5% from baseline"
+            comment
+            == "Error: TPUTCOMP: Throughput changed by 49.60%: baseline=1000.000 sypd, tolerance=5%, current=504.000 sypd"
         )
 
     @mock.patch("CIME.baselines.performance._perf_get_throughput")
@@ -431,7 +432,7 @@ def test_perf_compare_throughput_baseline(
         assert below_tolerance
         assert (
             comment
-            == "TPUTCOMP: Computation time changed by -0.80% relative to baseline"
+            == "TPUTCOMP: Throughput changed by -0.80%: baseline=500.000 sypd, tolerance=5%, current=504.000 sypd"
         )
 
     @mock.patch("CIME.baselines.performance.get_cpl_mem_usage")
@@ -466,7 +467,7 @@ def test_perf_compare_memory_baseline_no_baseline(
         assert below_tolerance
         assert (
             comment
-            == "MEMCOMP: Memory usage highwater has changed by 0.00% relative to baseline"
+            == "MEMCOMP: Memory usage highwater changed by 0.00%: baseline=0.000 MB, tolerance=5%, current=1003.000 MB"
         )
 
     @mock.patch("CIME.baselines.performance.get_cpl_mem_usage")
@@ -557,7 +558,7 @@ def test_perf_compare_memory_baseline_no_tolerance(
         assert below_tolerance
         assert (
             comment
-            == "MEMCOMP: Memory usage highwater has changed by 0.30% relative to baseline"
+            == "MEMCOMP: Memory usage highwater changed by 0.30%: baseline=1000.000 MB, tolerance=10%, current=1003.000 MB"
         )
 
     @mock.patch("CIME.baselines.performance.get_cpl_mem_usage")
@@ -592,7 +593,7 @@ def test_perf_compare_memory_baseline_above_threshold(
         assert not below_tolerance
         assert (
             comment
-            == "Error: Memory usage increase >5% from baseline's 1000.000000 to 2003.000000"
+            == "Error: MEMCOMP: Memory usage highwater changed by 100.30%: baseline=1000.000 MB, tolerance=5%, current=2003.000 MB"
         )
 
     @mock.patch("CIME.baselines.performance.get_cpl_mem_usage")
@@ -627,7 +628,7 @@ def test_perf_compare_memory_baseline(
         assert below_tolerance
         assert (
             comment
-            == "MEMCOMP: Memory usage highwater has changed by 0.30% relative to baseline"
+            == "MEMCOMP: Memory usage highwater changed by 0.30%: baseline=1000.000 MB, tolerance=5%, current=1003.000 MB"
         )
 
     def test_get_latest_cpl_logs_found_multiple(self):