Add test for relative_time

tests/test_pysnooper.py

@@ -50,6 +50,36 @@ def test_string_io():
     )
 
 
+def test_relative_time():
+    string_io = io.StringIO()
+
+    @pysnooper.snoop(string_io, relative_time=True)
+    def my_function(foo):
+        x = 7
+        y = 8
+        return y + x
+
+    result = my_function('baba')
+    assert result == 15
+    output = string_io.getvalue()
+    assert_output(
+        output,
+        (
+            SourcePathEntry(),
+            VariableEntry('foo', value_regex="u?'baba'"),
+            CallEntry('def my_function(foo):'),
+            LineEntry('x = 7'),
+            VariableEntry('x', '7'),
+            LineEntry('y = 8'),
+            VariableEntry('y', '8'),
+            LineEntry('return y + x'),
+            ReturnEntry('return y + x'),
+            ReturnValueEntry('15'),
+            ElapsedTimeEntry(),
+        )
+    )
+
+
 def test_thread_info():
 
     @pysnooper.snoop(thread_info=True)