Add combine --keep (#1110)

* Add combine --keep

Related to https://github.com/nedbat/coveragepy/issues/1108

* Fix unit tests

* Fix line too long

* Fix line too long

3 files changed, 28 insertions, 6 deletions

diff --git a/tests/test_api.py b/tests/test_api.py
index f8b7b4b2..62fd9ebc 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -442,7 +442,7 @@ class ApiTest(CoverageTest):
 
         cov2 = coverage.Coverage()
         with self.assertRaisesRegex(CoverageException, r"No data to combine"):
-            cov2.combine(strict=True)
+            cov2.combine(strict=True, keep=False)
 
         cov3 = coverage.Coverage()
         cov3.combine()
diff --git a/tests/test_cmdline.py b/tests/test_cmdline.py
index 374adb0d..3b11881b 100644
--- a/tests/test_cmdline.py
+++ b/tests/test_cmdline.py
@@ -218,20 +218,20 @@ class CmdLineTest(BaseCmdLineTest):
         # coverage combine with args
         self.cmd_executes("combine datadir1", """\
             cov = Coverage()
-            cov.combine(["datadir1"], strict=True)
+            cov.combine(["datadir1"], strict=True, keep=False)
             cov.save()
             """)
         # coverage combine, appending
         self.cmd_executes("combine --append datadir1", """\
             cov = Coverage()
             cov.load()
-            cov.combine(["datadir1"], strict=True)
+            cov.combine(["datadir1"], strict=True, keep=False)
             cov.save()
             """)
         # coverage combine without args
         self.cmd_executes("combine", """\
             cov = Coverage()
-            cov.combine(None, strict=True)
+            cov.combine(None, strict=True, keep=False)
             cov.save()
             """)
 
@@ -239,12 +239,12 @@ class CmdLineTest(BaseCmdLineTest):
         # https://github.com/nedbat/coveragepy/issues/385
         self.cmd_executes("combine --rcfile cov.ini", """\
             cov = Coverage(config_file='cov.ini')
-            cov.combine(None, strict=True)
+            cov.combine(None, strict=True, keep=False)
             cov.save()
             """)
         self.cmd_executes("combine --rcfile cov.ini data1 data2/more", """\
             cov = Coverage(config_file='cov.ini')
-            cov.combine(["data1", "data2/more"], strict=True)
+            cov.combine(["data1", "data2/more"], strict=True, keep=False)
             cov.save()
             """)
 
diff --git a/tests/test_process.py b/tests/test_process.py
index e4886156..b44147a3 100644
--- a/tests/test_process.py
+++ b/tests/test_process.py
@@ -244,6 +244,28 @@ class ProcessTest(CoverageTest):
         data.read()
         self.assertEqual(line_counts(data)['b_or_c.py'], 7)
 
+    def test_combine_parallel_data_keep(self):
+        self.make_b_or_c_py()
+        out = self.run_command("coverage run -p b_or_c.py b")
+        self.assertEqual(out, 'done\n')
+        self.assert_doesnt_exist(".coverage")
+        self.assert_file_count(".coverage.*", 1)
+
+        out = self.run_command("coverage run -p b_or_c.py c")
+        self.assertEqual(out, 'done\n')
+        self.assert_doesnt_exist(".coverage")
+
+        # After two -p runs, there should be two .coverage.machine.123 files.
+        self.assert_file_count(".coverage.*", 2)
+
+        # Combine the parallel coverage data files into .coverage with the keep flag.
+        self.run_command("coverage combine --keep")
+
+        # After combining, the .coverage file & the original combined file should still be there.
+        self.assert_exists(".coverage")
+        self.assert_file_count(".coverage.*", 2)
+
+
     def test_append_data(self):
         self.make_b_or_c_py()