Automatically select latest prereleases if only prereleases are avail…

…able

CHANGELOG.md

@@ -29,6 +29,7 @@
 - Changed the way virtualenvs are stored (names now depend on the project's path).
 - The `--git` option of the `add` command has been removed.
 - The `--path` option of the `add` command has been removed.
+- The `add` command will now automatically select the latest prerelease if only prereleases are available.
 
 ### Fixed
 

poetry/console/commands/init.py

@@ -321,7 +321,7 @@ def _find_best_version_for_package(
                 "Could not find a matching version of package {}".format(name)
             )
 
-        return (package.pretty_name, selector.find_recommended_require_version(package))
+        return package.pretty_name, selector.find_recommended_require_version(package)
 
     def _parse_requirements(
         self, requirements

poetry/version/version_selector.py

@@ -26,8 +26,9 @@ def find_best_candidate(
             constraint = parse_constraint("*")
 
         candidates = self._pool.find_packages(
-            package_name, constraint, allow_prereleases=allow_prereleases
+            package_name, constraint, allow_prereleases=True
         )
+        only_prereleases = all([c.version.is_prerelease() for c in candidates])
 
         if not candidates:
             return False
@@ -37,7 +38,12 @@ def find_best_candidate(
         # Select highest version if we have many
         package = candidates[0]
         for candidate in candidates:
-            if candidate.is_prerelease() and not dependency.allows_prereleases():
+            if (
+                candidate.is_prerelease()
+                and not dependency.allows_prereleases()
+                and not allow_prereleases
+                and not only_prereleases
+            ):
                 continue
 
             # Select highest version of the two
@@ -52,24 +58,20 @@ def find_recommended_require_version(self, package):
         return self._transform_version(version.text, package.pretty_version)
 
     def _transform_version(self, version, pretty_version):
-        # attempt to transform 2.1.1 to 2.1
-        # this allows you to upgrade through minor versions
         try:
             parsed = Version.parse(version)
             parts = [parsed.major, parsed.minor, parsed.patch]
         except ValueError:
             return pretty_version
 
-        # check to see if we have a semver-looking version
-        if len(parts) == 3:
-            # remove the last parts (the patch version number and any extra)
-            if parts[0] != 0:
-                del parts[2]
+        parts = parts[: parsed.precision]
 
+        # check to see if we have a semver-looking version
+        if len(parts) < 3:
+            version = pretty_version
+        else:
             version = ".".join(str(p) for p in parts)
             if parsed.is_prerelease():
                 version += "-{}".format(".".join(str(p) for p in parsed.prerelease))
-        else:
-            return pretty_version
 
         return "^{}".format(version)

tests/console/commands/test_add.py

@@ -499,3 +499,55 @@ def test_add_should_display_an_error_when_adding_existing_package_with_no_constr
         tester.execute("foo")
 
     assert "Package foo is already present" == str(e.value)
+
+
+def test_add_chooses_prerelease_if_only_prereleases_are_available(app, repo, installer):
+    command = app.find("add")
+    tester = CommandTester(command)
+
+    repo.add_package(get_package("foo", "1.2.3b0"))
+    repo.add_package(get_package("foo", "1.2.3b1"))
+
+    tester.execute("foo")
+
+    expected = """\
+Using version ^1.2.3-beta.1 for foo
+
+Updating dependencies
+Resolving dependencies...
+
+Writing lock file
+
+
+Package operations: 1 install, 0 updates, 0 removals
+
+  - Installing foo (1.2.3b1)
+"""
+
+    assert expected in tester.io.fetch_output()
+
+
+def test_add_preferes_stable_releases(app, repo, installer):
+    command = app.find("add")
+    tester = CommandTester(command)
+
+    repo.add_package(get_package("foo", "1.2.3"))
+    repo.add_package(get_package("foo", "1.2.4b1"))
+
+    tester.execute("foo")
+
+    expected = """\
+Using version ^1.2.3 for foo
+
+Updating dependencies
+Resolving dependencies...
+
+Writing lock file
+
+
+Package operations: 1 install, 0 updates, 0 removals
+
+  - Installing foo (1.2.3)
+"""
+
+    assert expected in tester.io.fetch_output()

tests/console/commands/test_init.py

@@ -88,10 +88,10 @@ def test_interactive_with_dependencies(app, repo, mocker, poetry):
 
 [tool.poetry.dependencies]
 python = "~2.7 || ^3.6"
-pendulum = "^2.0"
+pendulum = "^2.0.0"
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()
@@ -181,7 +181,7 @@ def test_interactive_with_git_dependencies(app, repo, mocker, poetry):
 demo = {git = "https://github.com/demo/demo.git"}
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()
@@ -231,7 +231,7 @@ def test_interactive_with_git_dependencies_with_reference(app, repo, mocker, poe
 demo = {git = "https://github.com/demo/demo.git", rev = "develop"}
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()
@@ -281,7 +281,7 @@ def test_interactive_with_git_dependencies_and_other_name(app, repo, mocker, poe
 demo = {git = "https://github.com/demo/pyproject-demo.git"}
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()
@@ -331,7 +331,7 @@ def test_interactive_with_directory_dependency(app, repo, mocker, poetry):
 demo = {path = "../../fixtures/git/github.com/demo/demo"}
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()
@@ -383,7 +383,7 @@ def test_interactive_with_directory_dependency_and_other_name(
 demo = {path = "../../fixtures/git/github.com/demo/pyproject-demo"}
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()
@@ -433,7 +433,7 @@ def test_interactive_with_file_dependency(app, repo, mocker, poetry):
 demo = {path = "../../fixtures/distributions/demo-0.1.0-py2.py3-none-any.whl"}
 
 [tool.poetry.dev-dependencies]
-pytest = "^3.6"
+pytest = "^3.6.0"
 """
 
     assert expected in tester.io.fetch_output()