Fix add command picking up prereleases by default

CHANGELOG.md

 # Change Log
 
+## [Unreleased]
+
+### Fixed
+
+- Fixed `add` command picking up prereleases by default.
+
+
 ## [0.8.1] - 2018-04-13
 
 ### Fixed

poetry/console/commands/add.py

@@ -14,6 +14,7 @@ class AddCommand(VenvCommand):
         { name* : Packages to add. }
         {--D|dev : Add package as development dependency. }
         {--optional : Add as an optional dependency. }
+        { --allow-prereleases : Accept prereleases. }
         {--dry-run : Outputs the operations but will not execute anything
                      (implicitly enables --verbose). }
     """
@@ -45,7 +46,10 @@ If you do not specify a version constraint, poetry will choose a suitable one ba
                         'Package {} is already present'.format(name)
                     )
 
-        requirements = self._determine_requirements(packages)
+        requirements = self._determine_requirements(
+            packages,
+            allow_prereleases=self.option('allow-prereleases')
+        )
         requirements = self._format_requirements(requirements)
 
         # validate requirements format
@@ -54,12 +58,19 @@ If you do not specify a version constraint, poetry will choose a suitable one ba
             parser.parse_constraints(constraint)
 
         for name, constraint in requirements.items():
+            if self.option('optional') or self.option('allow-prereleases'):
+                constraint = {
+                    'version': constraint
+                }
+
                 if self.option('optional'):
                     constraint = {
-                    'version': constraint,
                         'optional': True
                     }
 
+                if self.option('allow-prereleases'):
+                    constraint['allows-prereleases'] = True
+
             poetry_content[section][name] = constraint
 
         # Write new content
@@ -104,7 +115,8 @@ If you do not specify a version constraint, poetry will choose a suitable one ba
         return status
 
     def _determine_requirements(self,
-                                requires  # type: List[str]
+                                requires,  # type: List[str]
+                                allow_prereleases=False,  # type: bool
                                 ):  # type: (...) -> List[str]
         if not requires:
             return []
@@ -115,7 +127,8 @@ If you do not specify a version constraint, poetry will choose a suitable one ba
             if 'version' not in requirement:
                 # determine the best version automatically
                 name, version = self._find_best_version_for_package(
-                    requirement['name']
+                    requirement['name'],
+                    allow_prereleases=allow_prereleases
                 )
                 requirement['version'] = version
                 requirement['name'] = name
@@ -128,7 +141,8 @@ If you do not specify a version constraint, poetry will choose a suitable one ba
                 # check that the specified version/constraint exists
                 # before we proceed
                 name, _ = self._find_best_version_for_package(
-                    requirement['name'], requirement['version']
+                    requirement['name'], requirement['version'],
+                    allow_prereleases=allow_prereleases
                 )
 
                 requirement['name'] = name
@@ -141,12 +155,16 @@ If you do not specify a version constraint, poetry will choose a suitable one ba
 
     def _find_best_version_for_package(self,
                                        name,
-                                       required_version=None
+                                       required_version=None,
+                                       allow_prereleases=False
                                        ):  # type: (...) -> Tuple[str, str]
         from poetry.version.version_selector import VersionSelector
 
         selector = VersionSelector(self.poetry.pool)
-        package = selector.find_best_candidate(name, required_version)
+        package = selector.find_best_candidate(
+            name, required_version,
+            allow_prereleases=allow_prereleases
+        )
 
         if not package:
             # TODO: find similar

poetry/json/schemas/poetry-schema.json

@@ -179,7 +179,7 @@
                     "type": "string",
                     "description": "The python versions for which the dependency should be installed."
                 },
-                "allows_prereleases": {
+                "allows-prereleases": {
                     "type": "boolean",
                     "description": "Whether the dependency allows prereleases or not."
                 },
@@ -222,7 +222,7 @@
                     "type": "string",
                     "description": "The python versions for which the dependency should be installed."
                 },
-                "allows_prereleases": {
+                "allows-prereleases": {
                     "type": "boolean",
                     "description": "Whether the dependency allows prereleases or not."
                 },
@@ -252,7 +252,7 @@
                     "type": "string",
                     "description": "The python versions for which the dependency should be installed."
                 },
-                "allows_prereleases": {
+                "allows-prereleases": {
                     "type": "boolean",
                     "description": "Whether the dependency allows prereleases or not."
                 },

poetry/packages/package.py

@@ -260,7 +260,7 @@ class Package(object):
             optional = constraint.get('optional', False)
             python_versions = constraint.get('python')
             platform = constraint.get('platform')
-            allows_prereleases = constraint.get('allows_prereleases', False)
+            allows_prereleases = constraint.get('allows-prereleases', False)
 
             if 'git' in constraint:
                 # VCS dependency

poetry/version/version_selector.py

@@ -15,7 +15,8 @@ class VersionSelector(object):
 
     def find_best_candidate(self,
                             package_name,                 # type: str
-                            target_package_version=None  # type:  Union[str, None]
+                            target_package_version=None,  # type:  Union[str, None]
+                            allow_prereleases=False       # type: bool
                             ):  # type: (...) -> Union[Package, bool]
         """
         Given a package name and optional version,
@@ -34,6 +35,9 @@ class VersionSelector(object):
         # Select highest version if we have many
         package = candidates[0]
         for candidate in candidates:
+            if candidate.is_prerelease() and not allow_prereleases:
+                continue
+
             # Select highest version of the two
             if less_than(package.version, candidate.version):
                 package = candidate

tests/fixtures/complete.toml

@@ -22,7 +22,7 @@ toml = "^0.9"
 # Dependencies with extras
 requests = { version = "^2.13", extras = [ "security" ] }
 # Python specific dependencies with prereleases allowed
-pathlib2 = { version = "^2.2", python = "~2.7", allows_prereleases = true }
+pathlib2 = { version = "^2.2", python = "~2.7", allows-prereleases = true }
 # Git dependencies
 cleo = { git = "https://github.com/sdispater/cleo.git", branch = "master" }