From abdffbb1b91914637ded1d938d615a343f4aadd6 Mon Sep 17 00:00:00 2001
From: mfacchinelli <m.facchinelli@imperial.ac.uk>
Date: Thu, 1 Feb 2024 11:01:22 +0000
Subject: [PATCH] Update tests for science and HK for cropping

---
 src/data/+mag/HK.m         |  4 +++-
 src/data/+mag/Science.m    |  4 +++-
 tests/unit/data/tHK.m      | 19 +++++++++++++++++++
 tests/unit/data/tScience.m | 18 +++++++++++++++++-
 4 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/src/data/+mag/HK.m b/src/data/+mag/HK.m
index 1303b9da..05354ae1 100644
--- a/src/data/+mag/HK.m
+++ b/src/data/+mag/HK.m
@@ -52,7 +52,9 @@ function crop(this, timeFilter)
 
                 this(i).Data = this(i).Data(timeFilter, :);
 
-                if ~isempty(this(i).Time)
+                if isempty(this(i).Time)
+                    this(i).MetaData.Timestamp = NaT(TimeZone = mag.process.DateTime.TimeZone);
+                else
                     this(i).MetaData.Timestamp = this(i).Time(1);
                 end
             end
diff --git a/src/data/+mag/Science.m b/src/data/+mag/Science.m
index 86257966..8efe3fa5 100644
--- a/src/data/+mag/Science.m
+++ b/src/data/+mag/Science.m
@@ -102,7 +102,9 @@ function crop(this, timeFilter)
                 this.Data.Properties.Events = this.Data.Properties.Events(timePeriod, :);
             end
 
-            if ~isempty(this.Time)
+            if isempty(this.Time)
+                this.MetaData.Timestamp = NaT(TimeZone = mag.process.DateTime.TimeZone);
+            else
                 this.MetaData.Timestamp = this.Time(1);
             end
         end
diff --git a/tests/unit/data/tHK.m b/tests/unit/data/tHK.m
index 60ec76a6..cff33164 100644
--- a/tests/unit/data/tHK.m
+++ b/tests/unit/data/tHK.m
@@ -18,6 +18,25 @@ function cropMethod_timerange(testCase)
             testCase.cropAndVerify(data, timeFilter, expectedTimes, expectedData);
         end
 
+        % Test that "crop" method does not fail when no data is selected.
+        function cropMethod_noSelection(testCase)
+
+            % Set up.
+            data = testCase.createTestData();
+
+            % Exercise.
+            data.crop(timerange(datetime("Inf", TimeZone = "local"), datetime("-Inf", TimeZone = "local")));
+
+            % Verify.
+            for i = 1:numel(data)
+
+                testCase.verifyEmpty(data(i).IndependentVariable, "All data should be cropped out.");
+                testCase.verifyEmpty(data(i).DependentVariables, "All data should be cropped out.");
+
+                testCase.verifyTrue(ismissing(data(i).MetaData.Timestamp), "All data should be cropped out.");
+            end
+        end
+
         % Test that "resample" method can resample to a higher frequency.
         function resampleMethod_higherFrequency(testCase)
 
diff --git a/tests/unit/data/tScience.m b/tests/unit/data/tScience.m
index 1fb0388f..26ec90ef 100644
--- a/tests/unit/data/tScience.m
+++ b/tests/unit/data/tScience.m
@@ -63,6 +63,22 @@ function cropMethod_events(testCase)
             testCase.verifyEqual(data.Events.Time, data.Time, "Data should be cropped as expected.");
         end
 
+        % Test that "crop" method does not fail when no data is selected.
+        function cropMethod_noSelection(testCase)
+
+            % Set up.
+            data = testCase.createTestData();
+
+            % Exercise.
+            data.crop(timerange(datetime("Inf", TimeZone = "local"), datetime("-Inf", TimeZone = "local")));
+
+            % Verify.
+            testCase.verifyEmpty(data.IndependentVariable, "All data should be cropped out.");
+            testCase.verifyEmpty(data.DependentVariables, "All data should be cropped out.");
+
+            testCase.verifyTrue(ismissing(data.MetaData.Timestamp), "All data should be cropped out.");
+        end
+
         % Test that "resample" method can resample to a lower frequency.
         function resampleMethod_lowerFrequency(testCase)
 
@@ -189,7 +205,7 @@ function cropAndVerify(testCase, data, timeFilter, expectedTimes, expectedData)
         function [data, rawData] = createTestData()
 
             rawData = timetable(datetime("now", TimeZone = "UTC") + minutes(1:10)', (1:10)', (11:20)', (21:30)', 3 * ones(10, 1), (1:10)', VariableNames = ["x", "y", "z", "range", "sequence"]);
-            data = mag.Science(rawData, mag.meta.Science());
+            data = mag.Science(rawData, mag.meta.Science(Timestamp = datetime("now", TimeZone = "UTC")));
         end
     end
 end