By default run Mercurial tests + enable the topic extension from code (no need for config file)

.github/workflows/test.yml

@@ -106,6 +106,7 @@ jobs:
           python setup.py bdist_wheel
           pip install dist/*.whl
           pip freeze
+          pip install mercurial hg-evolve
 
       - name: "Run tests"
         run: |

Dockerfile

@@ -18,9 +18,8 @@ FROM alpine:${ALPINE_VERSION}
 # install python, git, bash, mercurial
 RUN apk add --no-cache git git-lfs python3 py-pip bash docker mercurial
 
-# install and activate the evolve and topic Mercurial extensions
+# install hg-evolve (Mercurial extensions)
 RUN pip3 install hg-evolve --user --no-cache-dir
-RUN mkdir -p /etc/mercurial/hgrc.d && echo -e "[extensions]\nevolve =\ntopic =\n" >  /etc/mercurial/hgrc.d/evolve.rc
 
 # install repo2docker
 COPY --from=0 /tmp/wheelhouse /tmp/wheelhouse

repo2docker/contentproviders/mercurial.py

@@ -1,38 +1,9 @@
 import subprocess
-import os
-from distutils.util import strtobool
 
 from .base import ContentProvider, ContentProviderException
 from ..utils import execute_cmd
 
-HG_EVOLVE_REQUIRED = strtobool(
-    os.environ.get("REPO2DOCKER_HG_EVOLVE_REQUIRED", "False")
-)
-
-if HG_EVOLVE_REQUIRED:
-    if "REPO2DOCKER_HG_REQUIRED" in os.environ:
-        HG_REQUIRED = strtobool(os.environ["REPO2DOCKER_HG_REQUIRED"])
-        if not HG_REQUIRED:
-            raise ValueError(
-                "Incompatible values for environment variables "
-                "REPO2DOCKER_HG_EVOLVE_REQUIRED=1 and REPO2DOCKER_HG_REQUIRED=0"
-            )
-    else:
-        HG_REQUIRED = True
-else:
-    HG_REQUIRED = strtobool(os.environ.get("REPO2DOCKER_HG_REQUIRED", "False"))
-
-
-def is_mercurial_available():
-    try:
-        subprocess.check_output(["hg", "version"])
-    except subprocess.CalledProcessError:
-        return False
-    return True
-
-
-if HG_REQUIRED and not is_mercurial_available():
-    raise RuntimeError("REPO2DOCKER_HG_REQUIRED but the command `hg` is not available")
+args_enabling_topic = ["--config", "extensions.topic="]
 
 
 class Mercurial(ContentProvider):
@@ -43,12 +14,11 @@ class Mercurial(ContentProvider):
             return None
         try:
             subprocess.check_output(
-                ["hg", "identify", source, "--config", "extensions.hggit=!"],
+                ["hg", "identify", source, "--config", "extensions.hggit=!"]
+                + args_enabling_topic,
                 stderr=subprocess.DEVNULL,
             )
         except subprocess.CalledProcessError:
-            # warning: if hg is not installed and `not HG_REQUIRED`,
-            # we return None even for a hg repo
             return None
 
         return {"repo": source, "ref": ref}
@@ -66,7 +36,7 @@ class Mercurial(ContentProvider):
                 output_dir,
                 "--config",
                 "phases.publish=False",
-            ]
+            ] + args_enabling_topic
             if ref is not None:
                 # don't update so the clone will include an empty working
                 # directory, the given ref will be updated out later
@@ -85,7 +55,7 @@ class Mercurial(ContentProvider):
         if ref is not None:
             try:
                 for line in execute_cmd(
-                    ["hg", "update", "--clean", ref],
+                    ["hg", "update", "--clean", ref] + args_enabling_topic,
                     cwd=output_dir,
                     capture=yield_output,
                 ):
@@ -96,7 +66,7 @@ class Mercurial(ContentProvider):
                 )
                 raise ValueError("Failed to update to ref {}".format(ref))
 
-        cmd = ["hg", "identify", "-i"]
+        cmd = ["hg", "identify", "-i"] + args_enabling_topic
         sha1 = subprocess.Popen(cmd, stdout=subprocess.PIPE, cwd=output_dir)
         self._node_id = sha1.stdout.read().decode().strip()
 

tests/unit/contentproviders/test_mercurial.py

@@ -1,33 +1,42 @@
 from pathlib import Path
 import subprocess
 from tempfile import TemporaryDirectory
+import os
+from distutils.util import strtobool
 
 import pytest
 
 from repo2docker.contentproviders import Mercurial
-from repo2docker.contentproviders.mercurial import (
-    HG_REQUIRED,
-    HG_EVOLVE_REQUIRED,
-    is_mercurial_available,
+from repo2docker.contentproviders.mercurial import args_enabling_topic
+
+SKIP_HG = strtobool(os.environ.get("REPO2DOCKER_SKIP_HG_TESTS", "False"))
+SKIP_HG_EVOLVE = SKIP_HG or strtobool(
+    os.environ.get("REPO2DOCKER_SKIP_HG_EVOLVE_TESTS", "False")
 )
 
-skip_if_no_hg = pytest.mark.skipif(
-    not HG_REQUIRED and not is_mercurial_available(),
-    reason="not HG_REQUIRED and Mercurial not available",
+skip_if_no_hg_tests = pytest.mark.skipif(
+    SKIP_HG,
+    reason="REPO2DOCKER_SKIP_HG_TESTS",
+)
+skip_if_no_evolve_tests = pytest.mark.skipif(
+    SKIP_HG_EVOLVE,
+    reason="REPO2DOCKER_SKIP_HG_EVOLVE_TESTS",
 )
 
-
-def is_evolve_available():
-    if not is_mercurial_available():
-        return False
-    output = subprocess.getoutput("hg version -v")
-    return " evolve " in output
+if SKIP_HG_EVOLVE:
+    args_enabling_topic = []
 
 
-EVOLVE_AVAILABLE = is_evolve_available()
+@skip_if_no_hg_tests
+def test_if_mercurial_is_available():
+    subprocess.check_output(["hg", "version"])
 
-if HG_EVOLVE_REQUIRED and not EVOLVE_AVAILABLE:
-    raise RuntimeError("HG_EVOLVE_REQUIRED and not EVOLVE_AVAILABLE")
+
+@skip_if_no_evolve_tests
+def test_if_topic_is_available():
+    """Check that the topic extension can be enabled"""
+    output = subprocess.getoutput("hg version -v --config extensions.topic=")
+    assert "failed to import extension topic" not in output
 
 
 def _add_content_to_hg(repo_dir):
@@ -39,19 +48,22 @@ def _add_content_to_hg(repo_dir):
     subprocess.check_call(["hg", "add", "test"], cwd=repo_dir)
     subprocess.check_call(["hg", "commit", "-m", "Test commit"], cwd=repo_dir)
 
-    if EVOLVE_AVAILABLE:
-        subprocess.check_call(["hg", "topic", "test-topic"], cwd=repo_dir)
-        subprocess.check_call(
-            ["hg", "commit", "-m", "Test commit in topic test-topic"],
-            cwd=repo_dir,
-        )
-        subprocess.check_call(["hg", "up", "default"], cwd=repo_dir)
+    if not SKIP_HG_EVOLVE:
+
+        def check_call(command):
+            subprocess.check_call(command + args_enabling_topic, cwd=repo_dir)
+
+        check_call(["hg", "topic", "test-topic"])
+        check_call(["hg", "commit", "-m", "Test commit in topic test-topic"])
+        check_call(["hg", "up", "default"])
 
 
 def _get_node_id(repo_dir):
     """Get repository's current commit node ID (currently SHA1)."""
     node_id = subprocess.Popen(
-        ["hg", "identify", "-i"], stdout=subprocess.PIPE, cwd=repo_dir
+        ["hg", "identify", "-i"] + args_enabling_topic,
+        stdout=subprocess.PIPE,
+        cwd=repo_dir,
     )
     return node_id.stdout.read().decode().strip()
 
@@ -77,7 +89,7 @@ def hg_repo_with_content(hg_repo):
     yield hg_repo, node_id
 
 
-@skip_if_no_hg
+@skip_if_no_hg_tests
 def test_detect_mercurial(hg_repo_with_content, repo_with_content):
     mercurial = Mercurial()
     assert mercurial.detect("this-is-not-a-directory") is None
@@ -90,7 +102,7 @@ def test_detect_mercurial(hg_repo_with_content, repo_with_content):
     assert mercurial.detect(hg_repo) == {"repo": hg_repo, "ref": None}
 
 
-@skip_if_no_hg
+@skip_if_no_hg_tests
 def test_clone(hg_repo_with_content):
     """Test simple hg clone to a target dir"""
     upstream, node_id = hg_repo_with_content
@@ -105,7 +117,7 @@ def test_clone(hg_repo_with_content):
         assert mercurial.content_id == node_id
 
 
-@skip_if_no_hg
+@skip_if_no_hg_tests
 def test_bad_ref(hg_repo_with_content):
     """
     Test trying to update to a ref that doesn't exist
@@ -118,11 +130,7 @@ def test_bad_ref(hg_repo_with_content):
                 pass
 
 
-@pytest.mark.skipif(
-    not HG_EVOLVE_REQUIRED and not EVOLVE_AVAILABLE,
-    reason="not HG_EVOLVE_REQUIRED and hg-evolve not available",
-)
-@skip_if_no_hg
+@skip_if_no_evolve_tests
 def test_ref_topic(hg_repo_with_content):
     """
     Test trying to update to a topic