Fix an error when adding a new package with prereleases in lock file

CHANGELOG.md

@@ -29,6 +29,7 @@ commands in project subdirectories.
 - Fixed `self:update` command for some installation.
 - Fixed handling of extras when building projects.
 - Fixed handling of wildcard dependencies wen packaging/publishing.
+- Fixed an error when adding a new packages with prereleases in lock file.
 
 
 ## [0.8.6] - 2018-04-30

poetry/installation/installer.py

@@ -153,9 +153,14 @@ class Installer:
                             to_fix = False
 
                     if to_fix:
-                        fixed.append(
-                            Dependency(candidate.name, candidate.version)
+                        dependency = Dependency(
+                            candidate.name,
+                            candidate.version,
+                            optional=candidate.optional,
+                            category=candidate.category,
+                            allows_prereleases=candidate.is_prerelease()
                         )
+                        fixed.append(dependency)
 
             solver = Solver(
                 self._package,

tests/installation/fixtures/with-category-change.test

+[[package]]
+name = "A"
+version = "1.0"
+description = ""
+category = "main"
+optional = false
+python-versions = "*"
+platform = "*"
+
+[[package]]
+name = "B"
+version = "1.1"
+description = ""
+category = "main"
+optional = false
+python-versions = "*"
+platform = "*"
+
+[package.dependencies]
+A = "^1.0"
+
+[metadata]
+python-versions = "*"
+platform = "*"
+content-hash = "123456789"
+
+[metadata.hashes]
+"A" = []
+"B" = []

tests/installation/fixtures/with-prereleases.test

+[[package]]
+name = "A"
+version = "1.0a2"
+description = ""
+category = "main"
+optional = false
+python-versions = "*"
+platform = "*"
+
+[[package]]
+name = "B"
+version = "1.1"
+description = ""
+category = "main"
+optional = false
+python-versions = "*"
+platform = "*"
+
+[metadata]
+python-versions = "*"
+platform = "*"
+content-hash = "123456789"
+
+[metadata.hashes]
+"A" = []
+"B" = []

tests/installation/test_installer.py

@@ -572,3 +572,80 @@ def test_run_installs_with_local_directory(installer, locker, repo, package):
     assert locker.written_data == expected
 
     assert len(installer.installer.installs) == 3
+
+
+def test_run_with_prereleases(installer, locker, repo, package):
+    locker.locked(True)
+    locker.mock_lock_data({
+        'package': [{
+            'name': 'A',
+            'version': '1.0a2',
+            'category': 'main',
+            'optional': False,
+            'platform': '*',
+            'python-versions': '*',
+            'checksum': []
+        }],
+        'metadata': {
+            'python-versions': '*',
+            'platform': '*',
+            'content-hash': '123456789',
+            'hashes': {
+                'A': [],
+            }
+        }
+    })
+    package_a = get_package('A', '1.0a2')
+    package_b = get_package('B', '1.1')
+    repo.add_package(package_a)
+    repo.add_package(package_b)
+
+    package.add_dependency('A', {'version': '*', 'allows-prereleases': True})
+    package.add_dependency('B', '^1.1')
+
+    installer.update(True)
+    installer.whitelist({'B': '^1.1'})
+
+    installer.run()
+    expected = fixture('with-prereleases')
+
+    assert locker.written_data == expected
+
+
+def test_run_changes_category_if_needed(installer, locker, repo, package):
+    locker.locked(True)
+    locker.mock_lock_data({
+        'package': [{
+            'name': 'A',
+            'version': '1.0',
+            'category': 'dev',
+            'optional': True,
+            'platform': '*',
+            'python-versions': '*',
+            'checksum': []
+        }],
+        'metadata': {
+            'python-versions': '*',
+            'platform': '*',
+            'content-hash': '123456789',
+            'hashes': {
+                'A': [],
+            }
+        }
+    })
+    package_a = get_package('A', '1.0')
+    package_b = get_package('B', '1.1')
+    package_b.add_dependency('A', '^1.0')
+    repo.add_package(package_a)
+    repo.add_package(package_b)
+
+    package.add_dependency('A', {'version': '^1.0', 'optional': True}, category='dev')
+    package.add_dependency('B', '^1.1')
+
+    installer.update(True)
+    installer.whitelist({'B': '^1.1'})
+
+    installer.run()
+    expected = fixture('with-category-change')
+
+    assert locker.written_data == expected