Merge #545

545: Fix list backends r=MatthieuDartiailh a=MatthieuDartiailh

- [x] Executed ``black . && isort -c . && flake8`` with no errors
- [x] The change is fully covered by automated unit tests (in pyvisa/pyvisa-py#269)
- [x] Added an entry to the CHANGES file


Co-authored-by: MatthieuDartiailh <marul@laposte.net>

.github/workflows/ci.yml

@@ -65,7 +65,7 @@ jobs:
       - name: Test with pytest
         run: |
           pip install pytest-cov
-          pytest --pyargs pyvisa --cov pyvisa --cov-report xml
+          pytest --pyargs pyvisa --cov pyvisa --cov-report xml -v
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v1
         with:

CHANGES

@@ -1,6 +1,12 @@
 PyVISA Changelog
 ================
 
+1.11.1 (unreleased)
+-------------------
+
+- fix the listing of available backends (Also not that we now return the backend
+  name as can be used to create a ResourceManger) PR #545
+
 1.11 (16-09-2020)
 -----------------
 

README.rst

@@ -9,7 +9,7 @@ PyVISA
     :target: https://github.com/pyvisa/pyvisa/actions
     :alt: Documentation building
 .. image:: https://dev.azure.com/pyvisa/pyvisa/_apis/build/status/pyvisa.keysight-assisted?branchName=master
-    :target: https://github.com/pyvisa/pyvisa/actions
+    :target: https://dev.azure.com/pyvisa/pyvisa/_build
     :alt: Keysight assisted testing
 .. image:: https://codecov.io/gh/pyvisa/pyvisa/branch/master/graph/badge.svg
     :target: https://codecov.io/gh/pyvisa/pyvisa

pyvisa/highlevel.py

@@ -2775,14 +2775,15 @@ def write_from_file(
 def list_backends() -> List[str]:
     """Return installed backends.
 
-    Backends are installed python packages named pyvisa-<something> where <something>
+    Backends are installed python packages named pyvisa_<something> where <something>
     is the name of the backend.
 
     """
     return ["ivi"] + [
-        name
+        name[7:]
         for (loader, name, ispkg) in pkgutil.iter_modules()
-        if name.startswith("pyvisa-") and not name.endswith("-script")
+        if (name.startswith("pyvisa_") or name.startswith("pyvisa-"))
+        and not name.endswith("-script")
     ]
 
 

pyvisa/testsuite/test_cmd_line_tools.py

@@ -30,7 +30,11 @@ def test_visa_main(self):
         print(result.stdout.strip())
         print()
         print(details.strip())
-        assert result.stdout.strip() == details.strip()
+        # Path difference can lead to subtle differences in the backends
+        # compare only the first lines.
+        assert (
+            result.stdout.strip().split("\n")[:16] == details.strip().split("\n")[:16]
+        )
 
         with Popen(["python", "-m", "visa", "shell"], stdin=PIPE, stdout=PIPE) as p:
             stdout, _ = p.communicate(b"exit")
@@ -51,9 +55,13 @@ def test_visa_info(self):
         """Test the visa info command line tool."""
         result = run("pyvisa-info", stdout=PIPE, universal_newlines=True)
         details = util.system_details_to_str(util.get_system_details())
-        assert result.stdout.strip() == details.strip()
+        # Path difference can lead to subtle differences in the backends
+        # compare only the first lines.
+        assert (
+            result.stdout.strip().split("\n")[:16] == details.strip().split("\n")[:16]
+        )
 
-    # TODO test backend selection: this not easy at all to assert
+    # TODO test backend selection: this is not easy at all to assert
     @require_visa_lib
     def test_visa_shell(self):
         """Test the visa shell function."""

pyvisa/testsuite/test_highlevel.py

@@ -88,6 +88,20 @@ def _init(self):
         assert "oserror" in msg[1]
         assert "error" in msg[2]
 
+    def test_list_backends(self):
+        """Test listing backends."""
+        highlevel._WRAPPERS.clear()
+
+        path = os.path.join(os.path.dirname(__file__), "fake-extensions")
+        sys.path.append(path)
+        try:
+            backends = highlevel.list_backends()
+        finally:
+            sys.path.remove(path)
+
+        assert "ivi" in backends
+        assert "test" in backends
+
     def test_get_wrapper_class(self):
         """Test retrieving a wrapper class."""
         highlevel._WRAPPERS.clear()