Add sem-ver tag support to git provider

- use sem-ver constraints to provide a git package
- add tests for git provider using tags
  - test a tag dependency
  - test a missing tag dependency
  - test a sem-ver tag dependency

poetry/puzzle/provider.py

@@ -10,6 +10,7 @@
 from tempfile import mkdtemp
 from typing import List
 
+from poetry import semver
 from poetry.packages import Dependency
 from poetry.packages import DependencyPackage
 from poetry.packages import DirectoryDependency
@@ -172,11 +173,38 @@ def search_for_vcs(self, dependency):  # type: (VCSDependency) -> List[Package]
         try:
             git = Git()
             git.clone(dependency.source, tmp_dir)
-            git.checkout(dependency.reference, tmp_dir)
-            revision = git.rev_parse(dependency.reference, tmp_dir).strip()
+            revision = None
+
+            if dependency.tag:
+                tags = git.tags(tmp_dir)
+                if dependency.tag in tags:
+                    git.checkout(dependency.tag, tmp_dir)
+                    revision = dependency.tag
+                elif semver.is_sem_ver_constraint(dependency.tag):
+                    # find the latest matching sem-ver tag and update dependency.tag etc.
+                    sem_ver_tags = git.sem_ver_tags(tmp_dir)
+                    constraint = semver.parse_single_constraint(dependency.tag)
+                    match = None
+                    for tag in reversed(sem_ver_tags):
+                        ver = semver.parse_single_constraint(tag)
+                        if constraint.allows(ver):
+                            match = str(ver)
+                            break
+                        if ver < constraint:
+                            break
+                    if match:
+                        dependency = VCSDependency(
+                            dependency.name,
+                            dependency.vcs,
+                            dependency.source,
+                            tag=match,
+                        )
+                        git.checkout(dependency.tag, tmp_dir)
+                        revision = dependency.tag
 
-            if dependency.tag or dependency.rev:
-                revision = dependency.reference
+            if revision is None:
+                git.checkout(dependency.reference, tmp_dir)
+                revision = git.rev_parse(dependency.reference, folder=tmp_dir).strip()
 
             directory_dependency = DirectoryDependency(
                 dependency.name,
@@ -188,7 +216,6 @@ def search_for_vcs(self, dependency):  # type: (VCSDependency) -> List[Package]
                 directory_dependency.extras.append(extra)
 
             package = self.search_for_directory(directory_dependency)[0]
-
             package.source_type = "git"
             package.source_url = dependency.source
             package.source_reference = revision

tests/puzzle/test_provider.py

@@ -1,3 +1,16 @@
+"""
+Test Provider
+-------------
+
+Notes:
+- git demo repo data is actually in:
+  - tests/fixtures/git/github.com/demo/demo
+- the git demo project has a package version 0.1.2 defined in:
+  - tests/fixtures/git/github.com/demo/demo/setup.py
+- git operation mocks are in:
+  - tests.conftest.git_mock
+"""
+
 import pytest
 
 from poetry.io import NullIO
@@ -95,6 +108,63 @@ def test_search_for_vcs_read_setup(provider, mocker):
     }
 
 
+@pytest.mark.skipif(not PY35, reason="AST parsing does not work for Python <3.4")
+def test_search_for_vcs_read_setup_with_single_tag(provider, mocker):
+    mocker.patch("poetry.utils.env.Env.get", return_value=MockEnv())
+
+    dependency = VCSDependency(
+        "demo", "git", "https://github.com/demo/demo.git", tag="0.1.2"
+    )
+    assert dependency.branch is None
+    assert dependency.rev is None
+    assert dependency.tag == "0.1.2"
+
+    packages = provider.search_for_vcs(dependency)
+    assert len(packages) == 1
+    package = packages[0]
+    assert package.name == "demo"
+    assert package.version.text == dependency.tag
+
+
+@pytest.mark.skipif(not PY35, reason="AST parsing does not work for Python <3.4")
+def test_search_for_vcs_read_setup_with_missing_tag(provider, mocker):
+    mocker.patch("poetry.utils.env.Env.get", return_value=MockEnv())
+
+    dependency = VCSDependency(
+        "demo", "git", "https://github.com/demo/demo.git", tag="0.20.0"
+    )
+    assert dependency.branch is None
+    assert dependency.rev is None
+    assert dependency.tag == "0.20.0"
+
+    packages = provider.search_for_vcs(dependency)
+    assert len(packages) == 1
+    package = packages[0]
+    assert package.name == "demo"
+    assert package.version.text != dependency.tag
+    assert package.version.text == "0.1.2"  # defaults to latest available
+
+
+@pytest.mark.skipif(not PY35, reason="AST parsing does not work for Python <3.4")
+def test_search_for_vcs_read_setup_with_sem_ver_tag(provider, mocker):
+    mocker.patch("poetry.utils.env.Env.get", return_value=MockEnv())
+
+    dependency = VCSDependency(
+        "demo", "git", "https://github.com/demo/demo.git", tag="~0.1.0"
+    )
+    assert dependency.branch is None
+    assert dependency.rev is None
+    assert dependency.tag == "~0.1.0"
+
+    packages = provider.search_for_vcs(dependency)
+    assert len(packages) == 1
+    # package 0.1.2 is fixed in tests/fixtures/git/github.com/demo/demo/setup.py
+    package = packages[0]
+    assert package.name == "demo"
+    assert package.version.text != dependency.tag
+    assert package.version.text == "0.1.2"
+
+
 @pytest.mark.skipif(not PY35, reason="AST parsing does not work for Python <3.4")
 def test_search_for_vcs_read_setup_with_extras(provider, mocker):
     mocker.patch("poetry.utils.env.Env.get", return_value=MockEnv())