diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7ad0bc3f69..35c22a27f68 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,35 @@
 # Change Log
 
+## [1.2.0a1] - 2021-05-21
+
+This release is the first testing release of the upcoming 1.2.0 version.
+
+It **drops** support for Python 2.7 and 3.5.
+
+### Added
+
+- Poetry now supports a plugin system to alter or expand Poetry's functionality. ([#3733](https://github.com/python-poetry/poetry/pull/3733))
+- Poetry now supports [PEP 610](https://www.python.org/dev/peps/pep-0610/). ([#3876](https://github.com/python-poetry/poetry/pull/3876))
+- Several configuration options to better control the way virtual environments are created are now available. ([#3157](https://github.com/python-poetry/poetry/pull/3157), [#3711](https://github.com/python-poetry/poetry/pull/3711)).
+- The `new` command now supports namespace packages. ([#2768](https://github.com/python-poetry/poetry/pull/2768))
+- The `add` command now supports the `--editable` option to add packages in editable mode. ([#3940](https://github.com/python-poetry/poetry/pull/3940))
+
+### Changed
+
+- Python 2.7 and 3.5 are no longer supported. ([#3405](https://github.com/python-poetry/poetry/pull/3405))
+- The usage of the `get-poetry.py` script is now deprecated and is replaced by the `install-poetry.py` script. ([#3706](https://github.com/python-poetry/poetry/pull/3706))
+- Directory dependencies are now in non-develop mode by default. ([poetry-core#98](https://github.com/python-poetry/poetry-core/pull/98))
+- Improved support for PEP 440 specific versions that do not abide by semantic versioning. ([poetry-core#140](https://github.com/python-poetry/poetry-core/pull/140))
+- Improved the CLI experience and performance by migrating to the latest version of Cleo. ([#3618](https://github.com/python-poetry/poetry/pull/3618))
+- Packages previously considered as unsafe (`pip`, `setuptools`, `wheels` and `distribute`) can now be managed as any other package. ([#2826](https://github.com/python-poetry/poetry/pull/2826))
+- The `new` command now defaults to the Markdown format for README files. ([#2768](https://github.com/python-poetry/poetry/pull/2768))
+
+### Fixed
+
+- Fixed an error where command line options were not taken into account when using the `run` command. ([#3618](https://github.com/python-poetry/poetry/pull/3618))
+- Fixed an error in the way custom repositories were resolved. ([#3406](https://github.com/python-poetry/poetry/pull/3406))
+
+
 ## [1.1.5] - 2021-03-04
 
 ### Fixed
@@ -1093,7 +1123,8 @@ Initial release
 
 
 
-[Unreleased]: https://github.com/python-poetry/poetry/compare/1.1.4...master
+[Unreleased]: https://github.com/python-poetry/poetry/compare/1.2.0a1...master
+[1.2.0a1]: https://github.com/python-poetry/poetry/compare/1.2.0a1
 [1.1.4]: https://github.com/python-poetry/poetry/compare/1.1.4
 [1.1.3]: https://github.com/python-poetry/poetry/compare/1.1.3
 [1.1.2]: https://github.com/python-poetry/poetry/releases/tag/1.1.2
diff --git a/poetry.lock b/poetry.lock
index ee407ef3ba4..26eb85c6f31 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -16,11 +16,11 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [[package]]
 name = "attrs"
-version = "21.1.0"
+version = "21.2.0"
 description = "Classes Without Boilerplate"
 category = "dev"
 optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
 
 [package.extras]
 dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface", "furo", "sphinx", "sphinx-notfound-page", "pre-commit"]
@@ -79,7 +79,7 @@ pycparser = "*"
 
 [[package]]
 name = "cfgv"
-version = "3.2.0"
+version = "3.3.0"
 description = "Validate configuration and produce human readable error messages."
 category = "dev"
 optional = false
@@ -121,6 +121,9 @@ category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
 
+[package.dependencies]
+toml = {version = "*", optional = true, markers = "extra == \"toml\""}
+
 [package.extras]
 toml = ["toml"]
 
@@ -217,7 +220,7 @@ lxml = ["lxml"]
 
 [[package]]
 name = "httpretty"
-version = "1.0.5"
+version = "1.1.2"
 description = "HTTP client mock for Python"
 category = "dev"
 optional = false
@@ -259,7 +262,7 @@ testing = ["packaging", "pep517", "importlib-resources (>=1.3)"]
 
 [[package]]
 name = "importlib-resources"
-version = "5.1.2"
+version = "5.1.3"
 description = "Read resources from Python packages"
 category = "main"
 optional = false
@@ -270,7 +273,7 @@ zipp = {version = ">=0.4", markers = "python_version < \"3.8\""}
 
 [package.extras]
 docs = ["sphinx", "jaraco.packaging (>=8.2)", "rst.linker (>=1.9)"]
-testing = ["pytest (>=4.6)", "pytest-checkdocs (>=1.2.3)", "pytest-flake8", "pytest-cov", "pytest-enabler", "pytest-black (>=0.3.7)", "pytest-mypy"]
+testing = ["pytest (>=4.6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytest-cov", "pytest-enabler (>=1.0.1)", "pytest-black (>=0.3.7)", "pytest-mypy"]
 
 [[package]]
 name = "iniconfig"
@@ -390,23 +393,16 @@ dev = ["pre-commit", "tox"]
 
 [[package]]
 name = "poetry-core"
-version = "1.1.0a4"
+version = "1.1.0a5"
 description = "Poetry PEP 517 Build Backend"
 category = "main"
 optional = false
-python-versions = "^3.6"
-develop = false
+python-versions = ">=3.6,<4.0"
 
 [package.dependencies]
 dataclasses = {version = ">=0.8", markers = "python_version >= \"3.6\" and python_version < \"3.7\""}
 importlib-metadata = {version = ">=1.7.0", markers = "python_version < \"3.8\""}
 
-[package.source]
-type = "git"
-url = "https://github.com/python-poetry/poetry-core.git"
-reference = "master"
-resolved_reference = "8b1cc5ea8d4557a4d215c873ebf2acfe282ad64d"
-
 [[package]]
 name = "pre-commit"
 version = "2.12.1"
@@ -489,14 +485,14 @@ testing = ["argcomplete", "hypothesis (>=3.56)", "mock", "nose", "requests", "xm
 
 [[package]]
 name = "pytest-cov"
-version = "2.11.1"
+version = "2.12.0"
 description = "Pytest plugin for measuring coverage."
 category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
 
 [package.dependencies]
-coverage = ">=5.2.1"
+coverage = {version = ">=5.2.1", extras = ["toml"]}
 pytest = ">=4.6"
 
 [package.extras]
@@ -620,7 +616,7 @@ python-versions = ">=2.6, !=3.0.*, !=3.1.*, !=3.2.*"
 
 [[package]]
 name = "tomlkit"
-version = "0.7.0"
+version = "0.7.2"
 description = "Style preserving TOML library"
 category = "main"
 optional = false
@@ -705,7 +701,7 @@ testing = ["pytest (>=4.6)", "pytest-checkdocs (>=1.2.3)", "pytest-flake8", "pyt
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.6"
-content-hash = "e38d34da68dcd63ef9f9d999f60b8e19d8da7f988031c3a6e6865d51c1fadeda"
+content-hash = "ac67bc6eacbb6b633f9568d69533d80456f632c7bfb9a2aa61aa9dd98e862473"
 
 [metadata.files]
 appdirs = [
@@ -717,8 +713,8 @@ atomicwrites = [
     {file = "atomicwrites-1.4.0.tar.gz", hash = "sha256:ae70396ad1a434f9c7046fd2dd196fc04b12f9e91ffb859164193be8b6168a7a"},
 ]
 attrs = [
-    {file = "attrs-21.1.0-py2.py3-none-any.whl", hash = "sha256:8ee1e5f5a1afc5b19bdfae4fdf0c35ed324074bdce3500c939842c8f818645d9"},
-    {file = "attrs-21.1.0.tar.gz", hash = "sha256:3901be1cb7c2a780f14668691474d9252c070a756be0a9ead98cfeabfa11aeb8"},
+    {file = "attrs-21.2.0-py2.py3-none-any.whl", hash = "sha256:149e90d6d8ac20db7a955ad60cf0e6881a3f20d37096140088356da6c716b0b1"},
+    {file = "attrs-21.2.0.tar.gz", hash = "sha256:ef6aaac3ca6cd92904cdd0d83f629a15f18053ec84e6432106f7a4d04ae4f5fb"},
 ]
 cachecontrol = [
     {file = "CacheControl-0.12.6-py2.py3-none-any.whl", hash = "sha256:10d056fa27f8563a271b345207402a6dcce8efab7e5b377e270329c62471b10d"},
@@ -772,8 +768,8 @@ cffi = [
     {file = "cffi-1.14.5.tar.gz", hash = "sha256:fd78e5fee591709f32ef6edb9a015b4aa1a5022598e36227500c8f4e02328d9c"},
 ]
 cfgv = [
-    {file = "cfgv-3.2.0-py2.py3-none-any.whl", hash = "sha256:32e43d604bbe7896fe7c248a9c2276447dbef840feb28fe20494f62af110211d"},
-    {file = "cfgv-3.2.0.tar.gz", hash = "sha256:cf22deb93d4bcf92f345a5c3cd39d3d41d6340adc60c78bbbd6588c384fda6a1"},
+    {file = "cfgv-3.3.0-py2.py3-none-any.whl", hash = "sha256:b449c9c6118fe8cca7fa5e00b9ec60ba08145d281d52164230a69211c5d597a1"},
+    {file = "cfgv-3.3.0.tar.gz", hash = "sha256:9e600479b3b99e8af981ecdfc80a0296104ee610cab48a5ae4ffd0b668650eb1"},
 ]
 chardet = [
     {file = "chardet-4.0.0-py2.py3-none-any.whl", hash = "sha256:f864054d66fd9118f2e67044ac8981a54775ec5b67aed0441892edb553d21da5"},
@@ -884,7 +880,7 @@ html5lib = [
     {file = "html5lib-1.1.tar.gz", hash = "sha256:b2e5b40261e20f354d198eae92afc10d750afb487ed5e50f9c4eaf07c184146f"},
 ]
 httpretty = [
-    {file = "httpretty-1.0.5.tar.gz", hash = "sha256:e53c927c4d3d781a0761727f1edfad64abef94e828718e12b672a678a8b3e0b5"},
+    {file = "httpretty-1.1.2.tar.gz", hash = "sha256:73d3e342ce8b21a16b0ff6c2b4c2c2d11c2da28784c264fcf7fe8cd2d8a25090"},
 ]
 identify = [
     {file = "identify-2.2.4-py2.py3-none-any.whl", hash = "sha256:ad9f3fa0c2316618dc4d840f627d474ab6de106392a4f00221820200f490f5a8"},
@@ -899,8 +895,8 @@ importlib-metadata = [
     {file = "importlib_metadata-1.7.0.tar.gz", hash = "sha256:90bb658cdbbf6d1735b6341ce708fc7024a3e14e99ffdc5783edea9f9b077f83"},
 ]
 importlib-resources = [
-    {file = "importlib_resources-5.1.2-py3-none-any.whl", hash = "sha256:ebab3efe74d83b04d6bf5cd9a17f0c5c93e60fb60f30c90f56265fce4682a469"},
-    {file = "importlib_resources-5.1.2.tar.gz", hash = "sha256:642586fc4740bd1cad7690f836b3321309402b20b332529f25617ff18e8e1370"},
+    {file = "importlib_resources-5.1.3-py3-none-any.whl", hash = "sha256:3b9c774e0e7e8d9c069eb2fe6aee7e9ae71759a381dec02eb45249fba7f38713"},
+    {file = "importlib_resources-5.1.3.tar.gz", hash = "sha256:0786b216556e53b34156263ab654406e543a8b0d9b1381019e25a36a09263c36"},
 ]
 iniconfig = [
     {file = "iniconfig-1.1.1-py2.py3-none-any.whl", hash = "sha256:011e24c64b7f47f6ebd835bb12a743f2fbe9a26d4cecaa7f53bc4f35ee9da8b3"},
@@ -971,7 +967,10 @@ pluggy = [
     {file = "pluggy-0.13.1-py2.py3-none-any.whl", hash = "sha256:966c145cd83c96502c3c3868f50408687b38434af77734af1e9ca461a4081d2d"},
     {file = "pluggy-0.13.1.tar.gz", hash = "sha256:15b2acde666561e1298d71b523007ed7364de07029219b604cf808bfa1c765b0"},
 ]
-poetry-core = []
+poetry-core = [
+    {file = "poetry-core-1.1.0a5.tar.gz", hash = "sha256:1b886de26026865325eae86a5d12eb154b80c0add8067c106eb706757594d85f"},
+    {file = "poetry_core-1.1.0a5-py3-none-any.whl", hash = "sha256:b347525c1417e9b5c6aee52967eff98c0886853a9e8ab1b9dfb2659913dd37bc"},
+]
 pre-commit = [
     {file = "pre_commit-2.12.1-py2.py3-none-any.whl", hash = "sha256:70c5ec1f30406250b706eda35e868b87e3e4ba099af8787e3e8b4b01e84f4712"},
     {file = "pre_commit-2.12.1.tar.gz", hash = "sha256:900d3c7e1bf4cf0374bb2893c24c23304952181405b4d88c9c40b72bda1bb8a9"},
@@ -1001,8 +1000,8 @@ pytest = [
     {file = "pytest-6.2.4.tar.gz", hash = "sha256:50bcad0a0b9c5a72c8e4e7c9855a3ad496ca6a881a3641b4260605450772c54b"},
 ]
 pytest-cov = [
-    {file = "pytest-cov-2.11.1.tar.gz", hash = "sha256:359952d9d39b9f822d9d29324483e7ba04a3a17dd7d05aa6beb7ea01e359e5f7"},
-    {file = "pytest_cov-2.11.1-py2.py3-none-any.whl", hash = "sha256:bdb9fdb0b85a7cc825269a4c56b48ccaa5c7e365054b6038772c32ddcdc969da"},
+    {file = "pytest-cov-2.12.0.tar.gz", hash = "sha256:8535764137fecce504a49c2b742288e3d34bc09eed298ad65963616cc98fd45e"},
+    {file = "pytest_cov-2.12.0-py2.py3-none-any.whl", hash = "sha256:95d4933dcbbacfa377bb60b29801daa30d90c33981ab2a79e9ab4452c165066e"},
 ]
 pytest-mock = [
     {file = "pytest-mock-3.6.1.tar.gz", hash = "sha256:40217a058c52a63f1042f0784f62009e976ba824c418cced42e88d5f40ab0e62"},
@@ -1066,8 +1065,8 @@ toml = [
     {file = "toml-0.10.2.tar.gz", hash = "sha256:b3bda1d108d5dd99f4a20d24d9c348e91c4db7ab1b749200bded2f839ccbe68f"},
 ]
 tomlkit = [
-    {file = "tomlkit-0.7.0-py2.py3-none-any.whl", hash = "sha256:6babbd33b17d5c9691896b0e68159215a9387ebfa938aa3ac42f4a4beeb2b831"},
-    {file = "tomlkit-0.7.0.tar.gz", hash = "sha256:ac57f29693fab3e309ea789252fcce3061e19110085aa31af5446ca749325618"},
+    {file = "tomlkit-0.7.2-py2.py3-none-any.whl", hash = "sha256:173ad840fa5d2aac140528ca1933c29791b79a374a0861a80347f42ec9328117"},
+    {file = "tomlkit-0.7.2.tar.gz", hash = "sha256:d7a454f319a7e9bd2e249f239168729327e4dd2d27b17dc68be264ad1ce36754"},
 ]
 tox = [
     {file = "tox-3.23.1-py2.py3-none-any.whl", hash = "sha256:b0b5818049a1c1997599d42012a637a33f24c62ab8187223fdd318fa8522637b"},
diff --git a/poetry/__version__.py b/poetry/__version__.py
index bc0be1b6fa5..7bfbef15537 100644
--- a/poetry/__version__.py
+++ b/poetry/__version__.py
@@ -1 +1 @@
-__version__ = "1.2.0a0"
+__version__ = "1.2.0a1"
diff --git a/pyproject.toml b/pyproject.toml
index 20bd1420866..68f78a25a50 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "poetry"
-version = "1.2.0a0"
+version = "1.2.0a1"
 description = "Python dependency management and packaging made easy."
 authors = [
     "Sébastien Eustace <sebastien@eustace.io>"
@@ -31,7 +31,7 @@ generate-setup-file = false
 [tool.poetry.dependencies]
 python = "^3.6"
 
-poetry-core = { git = "https://github.com/python-poetry/poetry-core.git", branch = "master"}
+poetry-core = "~1.1.0a5"
 cleo = "^1.0.0a1"
 crashtest = "^0.3.0"
 requests = "^2.18"
diff --git a/tests/console/commands/self/test_update.py b/tests/console/commands/self/test_update.py
index 7d5c43c01e2..396965e2e68 100644
--- a/tests/console/commands/self/test_update.py
+++ b/tests/console/commands/self/test_update.py
@@ -63,12 +63,14 @@ def test_self_update_can_update_from_recommended_installation(
 Package operations: 0 installs, 2 updates, 0 removals
 
   - Updating cleo (0.8.2 -> 1.0.0)
-  - Updating poetry (1.2.0a0 -> 1.2.0)
+  - Updating poetry ({} -> {})
 
 Updating the poetry script
 
-Poetry (1.2.0) is installed now. Great!
-"""
+Poetry ({}) is installed now. Great!
+""".format(
+        __version__, new_version, new_version
+    )
 
     assert tester.io.fetch_output() == expected_output