feat: warnings are now real warnings

This makes coverage warnings visible when running test suites under
pytest.  But it also means some uninteresting warnings would show up in
our own test suite, so we had to catch or suppress those.

1 files changed, 40 insertions, 36 deletions

diff --git a/tests/test_api.py b/tests/test_api.py
index d6a9c08a..885f3370 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -23,7 +23,7 @@ from coverage.files import abs_file, relative_filename
 from coverage.misc import import_local_file
 
 from tests.coveragetest import CoverageTest, TESTS_DIR, UsingModulesMixin
-from tests.helpers import assert_count_equal, change_dir, nice_file
+from tests.helpers import assert_count_equal, assert_coverage_warnings, change_dir, nice_file
 
 
 class ApiTest(CoverageTest):
@@ -300,9 +300,11 @@ class ApiTest(CoverageTest):
         # If nothing was measured, the file-touching didn't happen properly.
         self.make_file("foo/bar.py", "print('Never run')")
         self.make_file("test.py", "assert True")
-        cov = coverage.Coverage(source=["foo"])
-        self.start_import_stop(cov, "test")
-        cov.report()
+        with pytest.warns(Warning) as warns:
+            cov = coverage.Coverage(source=["foo"])
+            self.start_import_stop(cov, "test")
+            cov.report()
+        assert_coverage_warnings(warns, "No data was collected. (no-data-collected)")
         # Name         Stmts   Miss  Cover
         # --------------------------------
         # foo/bar.py       1      1     0%
@@ -517,18 +519,19 @@ class ApiTest(CoverageTest):
             import sys, os
             print("Hello")
             """)
-        cov = coverage.Coverage(source=["sys", "xyzzy", "quux"])
-        self.start_import_stop(cov, "hello")
-        cov.get_data()
-
-        out, err = self.stdouterr()
-        assert "Hello\n" in out
-        assert textwrap.dedent("""\
-            Coverage.py warning: Module sys has no Python source. (module-not-python)
-            Coverage.py warning: Module xyzzy was never imported. (module-not-imported)
-            Coverage.py warning: Module quux was never imported. (module-not-imported)
-            Coverage.py warning: No data was collected. (no-data-collected)
-            """) in err
+        with pytest.warns(Warning) as warns:
+            cov = coverage.Coverage(source=["sys", "xyzzy", "quux"])
+            self.start_import_stop(cov, "hello")
+            cov.get_data()
+
+        assert "Hello\n" == self.stdout()
+        assert_coverage_warnings(
+            warns,
+            "Module sys has no Python source. (module-not-python)",
+            "Module xyzzy was never imported. (module-not-imported)",
+            "Module quux was never imported. (module-not-imported)",
+            "No data was collected. (no-data-collected)",
+            )
 
     def test_warnings_suppressed(self):
         self.make_file("hello.py", """\
@@ -539,24 +542,25 @@ class ApiTest(CoverageTest):
             [run]
             disable_warnings = no-data-collected, module-not-imported
             """)
-        cov = coverage.Coverage(source=["sys", "xyzzy", "quux"])
-        self.start_import_stop(cov, "hello")
-        cov.get_data()
+        with pytest.warns(Warning) as warns:
+            cov = coverage.Coverage(source=["sys", "xyzzy", "quux"])
+            self.start_import_stop(cov, "hello")
+            cov.get_data()
 
-        out, err = self.stdouterr()
-        assert "Hello\n" in out
-        assert "Coverage.py warning: Module sys has no Python source. (module-not-python)" in err
-        assert "module-not-imported" not in err
-        assert "no-data-collected" not in err
+        assert "Hello\n" == self.stdout()
+        assert_coverage_warnings(warns, "Module sys has no Python source. (module-not-python)")
+        # No "module-not-imported" in warns
+        # No "no-data-collected" in warns
 
     def test_warn_once(self):
-        cov = coverage.Coverage()
-        cov.load()
-        cov._warn("Warning, warning 1!", slug="bot", once=True)
-        cov._warn("Warning, warning 2!", slug="bot", once=True)
-        err = self.stderr()
-        assert "Warning, warning 1!" in err
-        assert "Warning, warning 2!" not in err
+        with pytest.warns(Warning) as warns:
+            cov = coverage.Coverage()
+            cov.load()
+            cov._warn("Warning, warning 1!", slug="bot", once=True)
+            cov._warn("Warning, warning 2!", slug="bot", once=True)
+
+        assert_coverage_warnings(warns, "Warning, warning 1! (bot)")
+        # No "Warning, warning 2!" in warns
 
     def test_source_and_include_dont_conflict(self):
         # A bad fix made this case fail: https://github.com/nedbat/coveragepy/issues/541
@@ -683,12 +687,12 @@ class ApiTest(CoverageTest):
         cov = coverage.Coverage(source=["."])
         cov.set_option("run:dynamic_context", "test_function")
         cov.start()
-        # Switch twice, but only get one warning.
-        cov.switch_context("test1")                                     # pragma: nested
-        cov.switch_context("test2")                                     # pragma: nested
-        expected = "Coverage.py warning: Conflicting dynamic contexts (dynamic-conflict)\n"
-        assert expected == self.stderr()
+        with pytest.warns(Warning) as warns:
+            # Switch twice, but only get one warning.
+            cov.switch_context("test1")                                 # pragma: nested
+            cov.switch_context("test2")                                 # pragma: nested
         cov.stop()                                                      # pragma: nested
+        assert_coverage_warnings(warns, "Conflicting dynamic contexts (dynamic-conflict)")
 
     def test_switch_context_unstarted(self):
         # Coverage must be started to switch context