Replace format-version with min-version

  * "min-version" is specified as a <major>.<minor> point version
    and uses the installed BuildStream version instead of having
    a separate versioning number for the format.

  * The presence of "format-version" is now used to indicate
    that we might be loading a BuildStream 1 project.

  * For now, where parsing the version at startup is concerned, and
    also where `bst init` is concerned, we artificially bump the
    detected BuildStream version to 2.0 if we detect a version < 2.0,
    these exceptions can be removed once 2.0 is tagged and released.

Summary of changes:

  _project.py: Now parse "min-version" and detect "format-version" to
               warn about loading a BuildStream 1 project

  _versions.py: Remove obsolete BST_FORMAT_VERSION numbers from here

  data/projectconfig.yaml: Remove old "format-version" from defaults

  utils.py: Added new private _parse_version() helper function, and another
            _get_bst_api_version() to get an adjusted API version.

  frontend/app.py, frontend/cli.py: Updated `bst init` implementation

  testing (buildstream.testing): Updated testing utilities to generate
  and use projects with min-version instead of format-version.

  tests and examples: Updated to use min-version across the board.

5 files changed, 10 insertions, 8 deletions

diff --git a/tests/artifactcache/config.py b/tests/artifactcache/config.py
index a42d1e487..24d555860 100644
--- a/tests/artifactcache/config.py
+++ b/tests/artifactcache/config.py
@@ -116,6 +116,7 @@ def test_artifact_cache_precedence(tmpdir, override_caches, project_caches, user
     # Produce a fake user and project config with the cache configuration.
     user_config, project_config = configure_remote_caches(override_caches, project_caches, user_caches)
     project_config["name"] = "test"
+    project_config["min-version"] = "2.0"
 
     user_config_file = str(tmpdir.join("buildstream.conf"))
     _yaml.roundtrip_dump(user_config, file=user_config_file)
@@ -179,6 +180,7 @@ def test_only_one(cli, datafiles, override_caches, project_caches, user_caches):
     # Produce a fake user and project config with the cache configuration.
     user_config, project_config = configure_remote_caches(override_caches, project_caches, user_caches)
     project_config["name"] = "test"
+    project_config["min-version"] = "2.0"
 
     cli.configure(user_config)
 
@@ -226,15 +228,12 @@ def test_paths_for_artifact_config_are_expanded(tmpdir, monkeypatch, artifacts_c
 
     monkeypatch.setenv("HOME", str(tmpdir.join("homedir")))
 
+    project_config = {"name": "test", "min-version": "2.0"}
+    user_config = {}
     if in_user_config:
-        user_config = {"artifacts": artifacts_config}
-        project_config = {"name": "test"}
+        user_config["artifacts"] = artifacts_config
     else:
-        user_config = {}
-        project_config = {
-            "name": "test",
-            "artifacts": artifacts_config,
-        }
+        project_config["artifacts"] = artifacts_config
 
     user_config_file = str(tmpdir.join("buildstream.conf"))
     _yaml.roundtrip_dump(user_config, file=user_config_file)
diff --git a/tests/artifactcache/expiry/project.conf b/tests/artifactcache/expiry/project.conf
index 18db7dab7..e70dae3c7 100644
--- a/tests/artifactcache/expiry/project.conf
+++ b/tests/artifactcache/expiry/project.conf
@@ -1,5 +1,6 @@
 # Project config for cache expiry test
 name: test
+min-version: 2.0
 element-path: elements
 aliases:
   project_dir: file://{project_dir}
diff --git a/tests/artifactcache/junctions/parent/base/project.conf b/tests/artifactcache/junctions/parent/base/project.conf
index 951ea1a34..7e258e29f 100644
--- a/tests/artifactcache/junctions/parent/base/project.conf
+++ b/tests/artifactcache/junctions/parent/base/project.conf
@@ -1 +1,2 @@
 name: base
+min-version: 2.0
diff --git a/tests/artifactcache/junctions/parent/project.conf b/tests/artifactcache/junctions/parent/project.conf
index 620fb42dc..30a3839a8 100644
--- a/tests/artifactcache/junctions/parent/project.conf
+++ b/tests/artifactcache/junctions/parent/project.conf
@@ -1 +1,2 @@
 name: parent
+min-version: 2.0
diff --git a/tests/artifactcache/project/project.conf b/tests/artifactcache/project/project.conf
index 854e38693..5ba316874 100644
--- a/tests/artifactcache/project/project.conf
+++ b/tests/artifactcache/project/project.conf
@@ -1,4 +1,4 @@
 # Project config for frontend build test
 name: test
-
+min-version: 2.0
 element-path: elements