Merge branch 'issue-638-validate-all-files' into 'master'

Add support for default targets

See merge request BuildStream/buildstream!925

32 files changed, 519 insertions, 45 deletions

diff --git a/NEWS b/NEWS
index 2e13f1480..4576f767b 100644
--- a/NEWS
+++ b/NEWS
@@ -30,6 +30,10 @@ buildstream 1.3.1
     specific. Recommendation if you are building in Linux is to use the
     ones being used in freedesktop-sdk project, for example
 
+  o Running commands without elements specified will now attempt to use
+    the default targets defined in the project configuration.
+    If no default target is defined, all elements in the project will be used.
+
   o All elements must now be suffixed with `.bst`
     Attempting to use an element that does not have the `.bst` extension,
     will result in a warning.
diff --git a/buildstream/_context.py b/buildstream/_context.py
index 8b9f47bd6..f14f6b746 100644
--- a/buildstream/_context.py
+++ b/buildstream/_context.py
@@ -32,7 +32,7 @@ from ._message import Message, MessageType
 from ._profile import Topics, profile_start, profile_end
 from ._artifactcache import ArtifactCache
 from ._cas import CASCache
-from ._workspaces import Workspaces, WorkspaceProjectCache, WORKSPACE_PROJECT_FILE
+from ._workspaces import Workspaces, WorkspaceProjectCache
 from .plugin import _plugin_lookup
 from .sandbox import SandboxRemote
 
@@ -657,20 +657,6 @@ class Context():
             self._cascache = CASCache(self.artifactdir)
         return self._cascache
 
-    # guess_element()
-    #
-    # Attempts to interpret which element the user intended to run commands on
-    #
-    # Returns:
-    #    (str) The name of the element, or None if no element can be guessed
-    def guess_element(self):
-        workspace_project_dir, _ = utils._search_upward_for_files(self._directory, [WORKSPACE_PROJECT_FILE])
-        if workspace_project_dir:
-            workspace_project = self._workspace_project_cache.get(workspace_project_dir)
-            return workspace_project.get_default_element()
-        else:
-            return None
-
 
 # _node_get_option_str()
 #
diff --git a/buildstream/_frontend/cli.py b/buildstream/_frontend/cli.py
index fd088b63c..ab190aae4 100644
--- a/buildstream/_frontend/cli.py
+++ b/buildstream/_frontend/cli.py
@@ -342,7 +342,15 @@ def init(app, project_name, format_version, element_path, force):
                 type=click.Path(readable=False))
 @click.pass_obj
 def build(app, elements, all_, track_, track_save, track_all, track_except, track_cross_junctions):
-    """Build elements in a pipeline"""
+    """Build elements in a pipeline
+
+    Specifying no elements will result in building the default targets
+    of the project. If no default targets are configured, all project
+    elements will be built.
+
+    When this command is executed from a workspace directory, the default
+    is to build the workspace element.
+    """
 
     if (track_except or track_cross_junctions) and not (track_ or track_all):
         click.echo("ERROR: The --track-except and --track-cross-junctions options "
@@ -353,10 +361,12 @@ def build(app, elements, all_, track_, track_save, track_all, track_except, trac
         click.echo("WARNING: --track-save is deprecated, saving is now unconditional", err=True)
 
     with app.initialized(session_name="Build"):
-        if not all_ and not elements:
-            guessed_target = app.context.guess_element()
-            if guessed_target:
-                elements = (guessed_target,)
+        ignore_junction_targets = False
+
+        if not elements:
+            elements = app.project.get_default_targets()
+            # Junction elements cannot be built, exclude them from default targets
+            ignore_junction_targets = True
 
         if track_all:
             track_ = elements
@@ -365,6 +375,7 @@ def build(app, elements, all_, track_, track_save, track_all, track_except, trac
                          track_targets=track_,
                          track_except=track_except,
                          track_cross_junctions=track_cross_junctions,
+                         ignore_junction_targets=ignore_junction_targets,
                          build_all=all_)
 
 
@@ -390,6 +401,13 @@ def build(app, elements, all_, track_, track_save, track_all, track_except, trac
 def show(app, elements, deps, except_, order, format_):
     """Show elements in the pipeline
 
+    Specifying no elements will result in showing the default targets
+    of the project. If no default targets are configured, all project
+    elements will be shown.
+
+    When this command is executed from a workspace directory, the default
+    is to show the workspace element.
+
     By default this will show all of the dependencies of the
     specified target element.
 
@@ -436,9 +454,7 @@ def show(app, elements, deps, except_, order, format_):
     """
     with app.initialized():
         if not elements:
-            guessed_target = app.context.guess_element()
-            if guessed_target:
-                elements = (guessed_target,)
+            elements = app.project.get_default_targets()
 
         dependencies = app.stream.load_selection(elements,
                                                  selection=deps,
@@ -478,6 +494,9 @@ def show(app, elements, deps, except_, order, format_):
 def shell(app, element, sysroot, mount, isolate, build_, cli_buildtree, command):
     """Run a command in the target element's sandbox environment
 
+    When this command is executed from a workspace directory, the default
+    is to shell into the workspace element.
+
     This will stage a temporary sysroot for running the target
     element, assuming it has already been built and all required
     artifacts are in the local cache.
@@ -511,7 +530,7 @@ def shell(app, element, sysroot, mount, isolate, build_, cli_buildtree, command)
 
     with app.initialized():
         if not element:
-            element = app.context.guess_element()
+            element = app.project.get_default_target()
             if not element:
                 raise AppError('Missing argument "ELEMENT".')
 
@@ -581,6 +600,13 @@ def source():
 def source_fetch(app, elements, deps, track_, except_, track_cross_junctions):
     """Fetch sources required to build the pipeline
 
+    Specifying no elements will result in fetching the default targets
+    of the project. If no default targets are configured, all project
+    elements will be fetched.
+
+    When this command is executed from a workspace directory, the default
+    is to fetch the workspace element.
+
     By default this will only try to fetch sources which are
     required for the build plan of the specified target element,
     omitting sources for any elements which are already built
@@ -606,9 +632,7 @@ def source_fetch(app, elements, deps, track_, except_, track_cross_junctions):
 
     with app.initialized(session_name="Fetch"):
         if not elements:
-            guessed_target = app.context.guess_element()
-            if guessed_target:
-                elements = (guessed_target,)
+            elements = app.project.get_default_targets()
 
         app.stream.fetch(elements,
                          selection=deps,
@@ -636,6 +660,15 @@ def source_track(app, elements, deps, except_, cross_junctions):
     """Consults the specified tracking branches for new versions available
     to build and updates the project with any newly available references.
 
+    Specifying no elements will result in tracking the default targets
+    of the project. If no default targets are configured, all project
+    elements will be tracked.
+
+    When this command is executed from a workspace directory, the default
+    is to track the workspace element.
+
+    If no default is declared, all elements in the project will be tracked
+
     By default this will track just the specified element, but you can also
     update a whole tree of dependencies in one go.
 
@@ -647,9 +680,7 @@ def source_track(app, elements, deps, except_, cross_junctions):
     """
     with app.initialized(session_name="Track"):
         if not elements:
-            guessed_target = app.context.guess_element()
-            if guessed_target:
-                elements = (guessed_target,)
+            elements = app.project.get_default_targets()
 
         # Substitute 'none' for 'redirect' so that element redirections
         # will be done
@@ -685,6 +716,9 @@ def source_track(app, elements, deps, except_, cross_junctions):
 def source_checkout(app, element, location, force, deps, fetch_, except_,
                     tar, build_scripts):
     """Checkout sources of an element to the specified location
+
+    When this command is executed from a workspace directory, the default
+    is to checkout the sources of the workspace element.
     """
     if not element and not location:
         click.echo("ERROR: LOCATION is not specified", err=True)
@@ -697,7 +731,7 @@ def source_checkout(app, element, location, force, deps, fetch_, except_,
 
     with app.initialized():
         if not element:
-            element = app.context.guess_element()
+            element = app.project.get_default_target()
             if not element:
                 raise AppError('Missing argument "ELEMENT".')
 
@@ -763,7 +797,7 @@ def workspace_close(app, remove_dir, all_, elements):
         if not (all_ or elements):
             # NOTE: I may need to revisit this when implementing multiple projects
             # opening one workspace.
-            element = app.context.guess_element()
+            element = app.project.get_default_target()
             if element:
                 elements = (element,)
             else:
@@ -824,7 +858,7 @@ def workspace_reset(app, soft, track_, all_, elements):
     with app.initialized():
 
         if not (all_ or elements):
-            element = app.context.guess_element()
+            element = app.project.get_default_target()
             if element:
                 elements = (element,)
             else:
@@ -921,7 +955,11 @@ def artifact():
                 type=click.Path(readable=False))
 @click.pass_obj
 def artifact_checkout(app, force, deps, integrate, hardlinks, tar, directory, element):
-    """Checkout contents of an artifact"""
+    """Checkout contents of an artifact
+
+    When this command is executed from a workspace directory, the default
+    is to checkout the artifact of the workspace element.
+    """
     from ..element import Scope
 
     if hardlinks and tar is not None:
@@ -952,7 +990,7 @@ def artifact_checkout(app, force, deps, integrate, hardlinks, tar, directory, el
 
     with app.initialized():
         if not element:
-            element = app.context.guess_element()
+            element = app.project.get_default_target()
             if not element:
                 raise AppError('Missing argument "ELEMENT".')
 
@@ -980,6 +1018,13 @@ def artifact_checkout(app, force, deps, integrate, hardlinks, tar, directory, el
 def artifact_pull(app, elements, deps, remote):
     """Pull a built artifact from the configured remote artifact cache.
 
+    Specifying no elements will result in pulling the default targets
+    of the project. If no default targets are configured, all project
+    elements will be pulled.
+
+    When this command is executed from a workspace directory, the default
+    is to pull the workspace element.
+
     By default the artifact will be pulled one of the configured caches
     if possible, following the usual priority order. If the `--remote` flag
     is given, only the specified cache will be queried.
@@ -992,12 +1037,15 @@ def artifact_pull(app, elements, deps, remote):
     """
 
     with app.initialized(session_name="Pull"):
+        ignore_junction_targets = False
+
         if not elements:
-            guessed_target = app.context.guess_element()
-            if guessed_target:
-                elements = (guessed_target,)
+            elements = app.project.get_default_targets()
+            # Junction elements cannot be pulled, exclude them from default targets
+            ignore_junction_targets = True
 
-        app.stream.pull(elements, selection=deps, remote=remote)
+        app.stream.pull(elements, selection=deps, remote=remote,
+                        ignore_junction_targets=ignore_junction_targets)
 
 
 ##################################################################
@@ -1015,6 +1063,13 @@ def artifact_pull(app, elements, deps, remote):
 def artifact_push(app, elements, deps, remote):
     """Push a built artifact to a remote artifact cache.
 
+    Specifying no elements will result in pushing the default targets
+    of the project. If no default targets are configured, all project
+    elements will be pushed.
+
+    When this command is executed from a workspace directory, the default
+    is to push the workspace element.
+
     The default destination is the highest priority configured cache. You can
     override this by passing a different cache URL with the `--remote` flag.
 
@@ -1029,12 +1084,15 @@ def artifact_push(app, elements, deps, remote):
         all:   All dependencies
     """
     with app.initialized(session_name="Push"):
+        ignore_junction_targets = False
+
         if not elements:
-            guessed_target = app.context.guess_element()
-            if guessed_target:
-                elements = (guessed_target,)
+            elements = app.project.get_default_targets()
+            # Junction elements cannot be pushed, exclude them from default targets
+            ignore_junction_targets = True
 
-        app.stream.push(elements, selection=deps, remote=remote)
+        app.stream.push(elements, selection=deps, remote=remote,
+                        ignore_junction_targets=ignore_junction_targets)
 
 
 ################################################################
diff --git a/buildstream/_project.py b/buildstream/_project.py
index 1492fde77..3ec141d58 100644
--- a/buildstream/_project.py
+++ b/buildstream/_project.py
@@ -104,6 +104,9 @@ class Project():
         # Absolute path to where elements are loaded from within the project
         self.element_path = None
 
+        # Default target elements
+        self._default_targets = None
+
         # ProjectRefs for the main refs and also for junctions
         self.refs = ProjectRefs(self.directory, 'project.refs')
         self.junction_refs = ProjectRefs(self.directory, 'junction.refs')
@@ -228,7 +231,7 @@ class Project():
             'element-path', 'variables',
             'environment', 'environment-nocache',
             'split-rules', 'elements', 'plugins',
-            'aliases', 'name',
+            'aliases', 'name', 'defaults',
             'artifacts', 'options',
             'fail-on-overlap', 'shell', 'fatal-warnings',
             'ref-storage', 'sandbox', 'mirrors', 'remote-execution',
@@ -391,6 +394,44 @@ class Project():
         # Reset the element loader state
         Element._reset_load_state()
 
+    # get_default_target()
+    #
+    # Attempts to interpret which element the user intended to run a command on.
+    # This is for commands that only accept a single target element and thus,
+    # this only uses the workspace element (if invoked from workspace directory)
+    # and does not use the project default targets.
+    #
+    def get_default_target(self):
+        return self._invoked_from_workspace_element
+
+    # get_default_targets()
+    #
+    # Attempts to interpret which elements the user intended to run a command on.
+    # This is for commands that accept multiple target elements.
+    #
+    def get_default_targets(self):
+
+        # If _invoked_from_workspace_element has a value,
+        # a workspace element was found before a project config
+        # Therefore the workspace does not contain a project
+        if self._invoked_from_workspace_element:
+            return (self._invoked_from_workspace_element,)
+
+        # Default targets from project configuration
+        if self._default_targets:
+            return tuple(self._default_targets)
+
+        # If default targets are not configured, default to all project elements
+        default_targets = []
+        for root, _, files in os.walk(self.element_path):
+            for file in files:
+                if file.endswith(".bst"):
+                    rel_dir = os.path.relpath(root, self.element_path)
+                    rel_file = os.path.join(rel_dir, file).lstrip("./")
+                    default_targets.append(rel_file)
+
+        return tuple(default_targets)
+
     # _load():
     #
     # Loads the project configuration file in the project
@@ -456,6 +497,10 @@ class Project():
         self.config.options = OptionPool(self.element_path)
         self.first_pass_config.options = OptionPool(self.element_path)
 
+        defaults = _yaml.node_get(pre_config_node, Mapping, 'defaults')
+        _yaml.node_validate(defaults, ['targets'])
+        self._default_targets = _yaml.node_get(defaults, list, "targets")
+
         # Fatal warnings
         self._fatal_warnings = _yaml.node_get(pre_config_node, list, 'fatal-warnings', default_value=[])
 
diff --git a/buildstream/_stream.py b/buildstream/_stream.py
index 62eff1d8b..36b496e77 100644
--- a/buildstream/_stream.py
+++ b/buildstream/_stream.py
@@ -161,6 +161,7 @@ class Stream():
     #    track_targets (list of str): Specified targets for tracking
     #    track_except (list of str): Specified targets to except from tracking
     #    track_cross_junctions (bool): Whether tracking should cross junction boundaries
+    #    ignore_junction_targets (bool): Whether junction targets should be filtered out
     #    build_all (bool): Whether to build all elements, or only those
     #                      which are required to build the target.
     #
@@ -168,6 +169,7 @@ class Stream():
               track_targets=None,
               track_except=None,
               track_cross_junctions=False,
+              ignore_junction_targets=False,
               build_all=False):
 
         if build_all:
@@ -180,6 +182,7 @@ class Stream():
                        selection=selection, track_selection=PipelineSelection.ALL,
                        track_except_targets=track_except,
                        track_cross_junctions=track_cross_junctions,
+                       ignore_junction_targets=ignore_junction_targets,
                        use_artifact_config=True,
                        fetch_subprojects=True,
                        dynamic_plan=True)
@@ -291,6 +294,7 @@ class Stream():
     # Args:
     #    targets (list of str): Targets to pull
     #    selection (PipelineSelection): The selection mode for the specified targets
+    #    ignore_junction_targets (bool): Whether junction targets should be filtered out
     #    remote (str): The URL of a specific remote server to pull from, or None
     #
     # If `remote` specified as None, then regular configuration will be used
@@ -298,6 +302,7 @@ class Stream():
     #
     def pull(self, targets, *,
              selection=PipelineSelection.NONE,
+             ignore_junction_targets=False,
              remote=None):
 
         use_config = True
@@ -306,6 +311,7 @@ class Stream():
 
         elements, _ = self._load(targets, (),
                                  selection=selection,
+                                 ignore_junction_targets=ignore_junction_targets,
                                  use_artifact_config=use_config,
                                  artifact_remote_url=remote,
                                  fetch_subprojects=True)
@@ -325,6 +331,7 @@ class Stream():
     # Args:
     #    targets (list of str): Targets to push
     #    selection (PipelineSelection): The selection mode for the specified targets
+    #    ignore_junction_targets (bool): Whether junction targets should be filtered out
     #    remote (str): The URL of a specific remote server to push to, or None
     #
     # If `remote` specified as None, then regular configuration will be used
@@ -336,6 +343,7 @@ class Stream():
     #
     def push(self, targets, *,
              selection=PipelineSelection.NONE,
+             ignore_junction_targets=False,
              remote=None):
 
         use_config = True
@@ -344,6 +352,7 @@ class Stream():
 
         elements, _ = self._load(targets, (),
                                  selection=selection,
+                                 ignore_junction_targets=ignore_junction_targets,
                                  use_artifact_config=use_config,
                                  artifact_remote_url=remote,
                                  fetch_subprojects=True)
@@ -851,6 +860,7 @@ class Stream():
     #    except_targets (list of str): Specified targets to except from fetching
     #    track_except_targets (list of str): Specified targets to except from fetching
     #    track_cross_junctions (bool): Whether tracking should cross junction boundaries
+    #    ignore_junction_targets (bool): Whether junction targets should be filtered out
     #    use_artifact_config (bool): Whether to initialize artifacts with the config
     #    artifact_remote_url (bool): A remote url for initializing the artifacts
     #    fetch_subprojects (bool): Whether to fetch subprojects while loading
@@ -865,6 +875,7 @@ class Stream():
               except_targets=(),
               track_except_targets=(),
               track_cross_junctions=False,
+              ignore_junction_targets=False,
               use_artifact_config=False,
               artifact_remote_url=None,
               fetch_subprojects=False,
@@ -881,6 +892,10 @@ class Stream():
                                 rewritable=rewritable,
                                 fetch_subprojects=fetch_subprojects)
 
+        # Optionally filter out junction elements
+        if ignore_junction_targets:
+            elements = [e for e in elements if e.get_kind() != 'junction']
+
         # Hold on to the targets
         self.targets = elements
 
diff --git a/buildstream/_versions.py b/buildstream/_versions.py
index 8472a5b33..2563fa504 100644
--- a/buildstream/_versions.py
+++ b/buildstream/_versions.py
@@ -23,7 +23,7 @@
 # This version is bumped whenever enhancements are made
 # to the `project.conf` format or the core element format.
 #
-BST_FORMAT_VERSION = 20
+BST_FORMAT_VERSION = 21
 
 
 # The base BuildStream artifact version
diff --git a/buildstream/data/projectconfig.yaml b/buildstream/data/projectconfig.yaml
index e9bdaa160..2a6b09a15 100644
--- a/buildstream/data/projectconfig.yaml
+++ b/buildstream/data/projectconfig.yaml
@@ -167,3 +167,11 @@ shell:
   # Command to run when `bst shell` does not provide a command
   #
   command: [ 'sh', '-i' ]
+
+# Defaults for bst commands
+#
+defaults:
+
+  # Set default target elements to use when none are passed on the command line.
+  # If none are configured in the project, default to all project elements.
+  targets: []
diff --git a/doc/source/format_project.rst b/doc/source/format_project.rst
index c3555e0c1..f4dea333a 100644
--- a/doc/source/format_project.rst
+++ b/doc/source/format_project.rst
@@ -945,6 +945,44 @@ Host side environment variable expansion is also supported:
      - '${XDG_RUNTIME_DIR}/pulse/native'
 
 
+.. _project_default_targets:
+
+Default targets
+---------------
+When running BuildStream commands from a project directory or subdirectory
+without specifying any target elements on the command line, the default targets
+of the project will be used.  The default targets can be configured in the
+``defaults`` section as follows:
+
+.. code:: yaml
+
+   defaults:
+
+     # List of default target elements
+     targets:
+     - app.bst
+
+If no default targets are configured in ``project.conf``, BuildStream commands
+will default to all ``.bst`` files in the configured element path.
+
+Commands that cannot support junctions as target elements (``bst build``,
+``bst artifact push``, and ``bst artifact pull``) ignore junctions in the list
+of default targets.
+
+When running BuildStream commands from a workspace directory (that is not a
+BuildStream project directory), project default targets are not used and the
+workspace element will be used as the default target instead.
+
+``bst artifact checkout``, ``bst source checkout``, and ``bst shell`` are
+currently limited to a single target element and due to this, they currently
+do not use project default targets.  However, they still use the workspace
+element as default target when run from a workspace directory.
+
+.. note::
+
+   The ``targets`` configuration is available since :ref:`format version 21 <project_format_version>`
+
+
 .. _project_builtin_defaults:
 
 Builtin defaults
diff --git a/tests/frontend/buildcheckout.py b/tests/frontend/buildcheckout.py
index 8c7e22a85..b35b14820 100644
--- a/tests/frontend/buildcheckout.py
+++ b/tests/frontend/buildcheckout.py
@@ -2,6 +2,7 @@ import os
 import tarfile
 import hashlib
 import pytest
+import subprocess
 from tests.testutils import cli, create_repo, ALL_REPO_KINDS, generate_junction
 from tests.testutils.site import IS_WINDOWS
 
@@ -61,6 +62,35 @@ def test_build_checkout(datafiles, cli, strict, hardlinks):
     assert os.path.exists(filename)
 
 
+@pytest.mark.datafiles(DATA_DIR + "_world")
+def test_build_default_all(datafiles, cli):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    result = cli.run(project=project, silent=True, args=['build'])
+
+    result.assert_success()
+    target_dir = os.path.join(cli.directory, DATA_DIR + "_world", "elements")
+    output_dir = os.path.join(cli.directory, "logs", "test")
+
+    expected = subprocess.Popen(('ls', target_dir), stdout=subprocess.PIPE)
+    expected = subprocess.check_output(("wc", "-w"), stdin=expected.stdout)
+
+    results = subprocess.Popen(('ls', output_dir), stdout=subprocess.PIPE)
+    results = subprocess.check_output(("wc", "-w"), stdin=results.stdout)
+
+    assert results == expected
+
+
+@pytest.mark.datafiles(DATA_DIR + "_default")
+def test_build_default(cli, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    result = cli.run(project=project, silent=True, args=['build'])
+
+    result.assert_success()
+    results = cli.get_element_state(project, "target2.bst")
+    expected = "cached"
+    assert results == expected
+
+
 @pytest.mark.datafiles(DATA_DIR)
 @pytest.mark.parametrize("strict,hardlinks", [
     ("non-strict", "hardlinks"),
@@ -550,6 +580,53 @@ def test_build_checkout_junction(cli, tmpdir, datafiles):
     assert contents == 'animal=Pony\n'
 
 
+# Test that default targets work with projects with junctions
+@pytest.mark.datafiles(DATA_DIR + "_world")
+def test_build_checkout_junction_default_targets(cli, tmpdir, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    subproject_path = os.path.join(project, 'files', 'sub-project')
+    junction_path = os.path.join(project, 'elements', 'junction.bst')
+    element_path = os.path.join(project, 'elements', 'junction-dep.bst')
+    checkout = os.path.join(cli.directory, 'checkout')
+
+    # Create a repo to hold the subproject and generate a junction element for it
+    ref = generate_junction(tmpdir, subproject_path, junction_path)
+
+    # Create a stack element to depend on a cross junction element
+    #
+    element = {
+        'kind': 'stack',
+        'depends': [
+            {
+                'junction': 'junction.bst',
+                'filename': 'import-etc.bst'
+            }
+        ]
+    }
+    _yaml.dump(element, element_path)
+
+    # Now try to build it, this should automatically result in fetching
+    # the junction itself at load time.
+    result = cli.run(project=project, args=['build'])
+    result.assert_success()
+
+    # Assert that it's cached now
+    assert cli.get_element_state(project, 'junction-dep.bst') == 'cached'
+
+    # Now check it out
+    result = cli.run(project=project, args=[
+        'artifact', 'checkout', 'junction-dep.bst', '--directory', checkout
+    ])
+    result.assert_success()
+
+    # Assert the content of /etc/animal.conf
+    filename = os.path.join(checkout, 'etc', 'animal.conf')
+    assert os.path.exists(filename)
+    with open(filename, 'r') as f:
+        contents = f.read()
+    assert contents == 'animal=Pony\n'
+
+
 @pytest.mark.datafiles(DATA_DIR)
 def test_build_checkout_workspaced_junction(cli, tmpdir, datafiles):
     project = os.path.join(datafiles.dirname, datafiles.basename)
diff --git a/tests/frontend/fetch.py b/tests/frontend/fetch.py
index 96c4a9335..24d9a36a6 100644
--- a/tests/frontend/fetch.py
+++ b/tests/frontend/fetch.py
@@ -49,6 +49,41 @@ def test_fetch(cli, tmpdir, datafiles, kind):
     assert cli.get_element_state(project, element_name) == 'buildable'
 
 
+@pytest.mark.datafiles(os.path.join(TOP_DIR, 'project_world'))
+def test_fetch_default_targets(cli, tmpdir, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    element_path = os.path.join(project, 'elements')
+    element_name = 'fetch-test.bst'
+
+    # Create our repo object of the given source type with
+    # the bin files, and then collect the initial ref.
+    #
+    repo = create_repo('git', str(tmpdir))
+    ref = repo.create(project)
+
+    # Write out our test target
+    element = {
+        'kind': 'import',
+        'sources': [
+            repo.source_config(ref=ref)
+        ]
+    }
+    _yaml.dump(element,
+               os.path.join(element_path,
+                            element_name))
+
+    # Assert that a fetch is needed
+    assert cli.get_element_state(project, element_name) == 'fetch needed'
+
+    # Now try to fetch it, using the default target feature
+    result = cli.run(project=project, args=['source', 'fetch'])
+    result.assert_success()
+
+    # Assert that we are now buildable because the source is
+    # now cached.
+    assert cli.get_element_state(project, element_name) == 'buildable'
+
+
 @pytest.mark.datafiles(os.path.join(TOP_DIR, 'consistencyerror'))
 def test_fetch_consistency_error(cli, tmpdir, datafiles):
     project = os.path.join(datafiles.dirname, datafiles.basename)
diff --git a/tests/frontend/project_default/elements/target.bst b/tests/frontend/project_default/elements/target.bst
new file mode 100644
index 000000000..d644c89ba
--- /dev/null
+++ b/tests/frontend/project_default/elements/target.bst
@@ -0,0 +1,4 @@
+kind: stack
+description: |
+
+  Main stack target for the bst build test
diff --git a/tests/frontend/project_default/elements/target2.bst b/tests/frontend/project_default/elements/target2.bst
new file mode 100644
index 000000000..d644c89ba
--- /dev/null
+++ b/tests/frontend/project_default/elements/target2.bst
@@ -0,0 +1,4 @@
+kind: stack
+description: |
+
+  Main stack target for the bst build test
diff --git a/tests/frontend/project_default/project.conf b/tests/frontend/project_default/project.conf
new file mode 100644
index 000000000..5987c82f1
--- /dev/null
+++ b/tests/frontend/project_default/project.conf
@@ -0,0 +1,11 @@
+# Project config for frontend build test
+name: test
+
+element-path: elements
+
+fatal-warnings:
+- bad-element-suffix
+
+defaults:
+ targets:
+ - target2.bst
diff --git a/tests/frontend/project_fail/elements/compose-all.bst b/tests/frontend/project_fail/elements/compose-all.bst
new file mode 100644
index 000000000..9b981dd73
--- /dev/null
+++ b/tests/frontend/project_fail/elements/compose-all.bst
@@ -0,0 +1,10 @@
+kind: compose
+
+depends:
+- fileNAME: import-dev.bst
+  type: build
+
+config:
+  # Dont try running the sandbox, we dont have a
+  # runtime to run anything in this context.
+  integrate: False
diff --git a/tests/frontend/project_fail/elements/import-dev.bst b/tests/frontend/project_fail/elements/import-dev.bst
new file mode 100644
index 000000000..152a54667
--- /dev/null
+++ b/tests/frontend/project_fail/elements/import-dev.bst
@@ -0,0 +1,4 @@
+kind: import
+sources:
+- kind: local
+  path: files/dev-files
diff --git a/tests/frontend/project_fail/elements/target.bst b/tests/frontend/project_fail/elements/target.bst
new file mode 100644
index 000000000..154c477e6
--- /dev/null
+++ b/tests/frontend/project_fail/elements/target.bst
@@ -0,0 +1,7 @@
+kind: stack
+description: |
+
+  Main stack target for the bst build test
+
+depends:
+- compose-all.bst
diff --git a/tests/frontend/project_fail/files/dev-files/usr/include/pony.h b/tests/frontend/project_fail/files/dev-files/usr/include/pony.h
new file mode 100644
index 000000000..40bd0c2e7
--- /dev/null
+++ b/tests/frontend/project_fail/files/dev-files/usr/include/pony.h
@@ -0,0 +1,12 @@
+#ifndef __PONY_H__
+#define __PONY_H__
+
+#define PONY_BEGIN "Once upon a time, there was a pony."
+#define PONY_END "And they lived happily ever after, the end."
+
+#define MAKE_PONY(story)  \
+  PONY_BEGIN \
+  story \
+  PONY_END
+
+#endif /* __PONY_H__ */
diff --git a/tests/frontend/project_fail/project.conf b/tests/frontend/project_fail/project.conf
new file mode 100644
index 000000000..854e38693
--- /dev/null
+++ b/tests/frontend/project_fail/project.conf
@@ -0,0 +1,4 @@
+# Project config for frontend build test
+name: test
+
+element-path: elements
diff --git a/tests/frontend/project_world/elements/checkout-deps.bst b/tests/frontend/project_world/elements/checkout-deps.bst
new file mode 100644
index 000000000..e3a548690
--- /dev/null
+++ b/tests/frontend/project_world/elements/checkout-deps.bst
@@ -0,0 +1,7 @@
+kind: stack
+description: It is important for this element to have both build and runtime dependencies
+depends:
+- filename: import-dev.bst
+  type: build
+- filename: import-bin.bst
+  type: runtime
diff --git a/tests/frontend/project_world/elements/compose-all.bst b/tests/frontend/project_world/elements/compose-all.bst
new file mode 100644
index 000000000..ba47081b3
--- /dev/null
+++ b/tests/frontend/project_world/elements/compose-all.bst
@@ -0,0 +1,12 @@
+kind: compose
+
+depends:
+- filename: import-bin.bst
+  type: build
+- filename: import-dev.bst
+  type: build
+
+config:
+  # Dont try running the sandbox, we dont have a
+  # runtime to run anything in this context.
+  integrate: False
diff --git a/tests/frontend/project_world/elements/compose-exclude-dev.bst b/tests/frontend/project_world/elements/compose-exclude-dev.bst
new file mode 100644
index 000000000..75c14378c
--- /dev/null
+++ b/tests/frontend/project_world/elements/compose-exclude-dev.bst
@@ -0,0 +1,16 @@
+kind: compose
+
+depends:
+- filename: import-bin.bst
+  type: build
+- filename: import-dev.bst
+  type: build
+
+config:
+  # Dont try running the sandbox, we dont have a
+  # runtime to run anything in this context.
+  integrate: False
+
+  # Exclude the dev domain
+  exclude:
+  - devel
diff --git a/tests/frontend/project_world/elements/compose-include-bin.bst b/tests/frontend/project_world/elements/compose-include-bin.bst
new file mode 100644
index 000000000..9571203c6
--- /dev/null
+++ b/tests/frontend/project_world/elements/compose-include-bin.bst
@@ -0,0 +1,16 @@
+kind: compose
+
+depends:
+- filename: import-bin.bst
+  type: build
+- filename: import-dev.bst
+  type: build
+
+config:
+  # Dont try running the sandbox, we dont have a
+  # runtime to run anything in this context.
+  integrate: False
+
+  # Only include the runtim
+  include:
+  - runtime
diff --git a/tests/frontend/project_world/elements/import-bin.bst b/tests/frontend/project_world/elements/import-bin.bst
new file mode 100644
index 000000000..066a03328
--- /dev/null
+++ b/tests/frontend/project_world/elements/import-bin.bst
@@ -0,0 +1 @@
+kind: stack
diff --git a/tests/frontend/project_world/elements/import-dev.bst b/tests/frontend/project_world/elements/import-dev.bst
new file mode 100644
index 000000000..066a03328
--- /dev/null
+++ b/tests/frontend/project_world/elements/import-dev.bst
@@ -0,0 +1 @@
+kind: stack
diff --git a/tests/frontend/project_world/elements/rebuild-target.bst b/tests/frontend/project_world/elements/rebuild-target.bst
new file mode 100644
index 000000000..49a02c217
--- /dev/null
+++ b/tests/frontend/project_world/elements/rebuild-target.bst
@@ -0,0 +1,4 @@
+kind: compose
+
+build-depends:
+- target.bst
diff --git a/tests/frontend/project_world/elements/target.bst b/tests/frontend/project_world/elements/target.bst
new file mode 100644
index 000000000..b9432fafa
--- /dev/null
+++ b/tests/frontend/project_world/elements/target.bst
@@ -0,0 +1,8 @@
+kind: stack
+description: |
+
+  Main stack target for the bst build test
+
+depends:
+- import-bin.bst
+- compose-all.bst
diff --git a/tests/frontend/project_world/files/sub-project/elements/import-etc.bst b/tests/frontend/project_world/files/sub-project/elements/import-etc.bst
new file mode 100644
index 000000000..f0171990e
--- /dev/null
+++ b/tests/frontend/project_world/files/sub-project/elements/import-etc.bst
@@ -0,0 +1,4 @@
+kind: import
+sources:
+- kind: local
+  path: files/etc-files
diff --git a/tests/frontend/project_world/files/sub-project/files/etc-files/etc/animal.conf b/tests/frontend/project_world/files/sub-project/files/etc-files/etc/animal.conf
new file mode 100644
index 000000000..db8c36cba
--- /dev/null
+++ b/tests/frontend/project_world/files/sub-project/files/etc-files/etc/animal.conf
@@ -0,0 +1 @@
+animal=Pony
diff --git a/tests/frontend/project_world/files/sub-project/project.conf b/tests/frontend/project_world/files/sub-project/project.conf
new file mode 100644
index 000000000..bbb8414a3
--- /dev/null
+++ b/tests/frontend/project_world/files/sub-project/project.conf
@@ -0,0 +1,4 @@
+# Project config for frontend build test
+name: subtest
+
+element-path: elements
diff --git a/tests/frontend/project_world/project.conf b/tests/frontend/project_world/project.conf
new file mode 100644
index 000000000..a7e4a023c
--- /dev/null
+++ b/tests/frontend/project_world/project.conf
@@ -0,0 +1,7 @@
+# Project config for frontend build test
+name: test
+
+element-path: elements
+
+fatal-warnings:
+- bad-element-suffix
diff --git a/tests/frontend/pull.py b/tests/frontend/pull.py
index f0d6fbf4e..20b740948 100644
--- a/tests/frontend/pull.py
+++ b/tests/frontend/pull.py
@@ -80,6 +80,56 @@ def test_push_pull_all(cli, tmpdir, datafiles):
 
 # Tests that:
 #
+#  * `bst push` (default targets) pushes all built elements to configured 'push' cache
+#  * `bst pull` (default targets) downloads everything from cache after local deletion
+#
+@pytest.mark.datafiles(DATA_DIR + '_world')
+def test_push_pull_default_targets(cli, tmpdir, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+
+    with create_artifact_share(os.path.join(str(tmpdir), 'artifactshare')) as share:
+
+        # First build the target elements
+        cli.configure({
+            'artifacts': {'url': share.repo}
+        })
+        result = cli.run(project=project, args=['build'])
+        result.assert_success()
+        assert cli.get_element_state(project, 'target.bst') == 'cached'
+
+        # Push all elements
+        cli.configure({
+            'artifacts': {'url': share.repo, 'push': True}
+        })
+        result = cli.run(project=project, args=['artifact', 'push'])
+        result.assert_success()
+
+        # Assert that everything is now cached in the remote.
+        all_elements = ['target.bst', 'import-bin.bst', 'import-dev.bst', 'compose-all.bst']
+        for element_name in all_elements:
+            assert_shared(cli, share, project, element_name)
+
+        # Now we've pushed, delete the user's local artifact cache
+        # directory and try to redownload it from the share
+        #
+        artifacts = os.path.join(cli.directory, 'artifacts')
+        shutil.rmtree(artifacts)
+
+        # Assert that nothing is cached locally anymore
+        states = cli.get_element_states(project, all_elements)
+        assert not any(states[e] == 'cached' for e in all_elements)
+
+        # Now try bst pull
+        result = cli.run(project=project, args=['artifact', 'pull'])
+        result.assert_success()
+
+        # And assert that it's again in the local cache, without having built
+        states = cli.get_element_states(project, all_elements)
+        assert not any(states[e] != 'cached' for e in all_elements)
+
+
+# Tests that:
+#
 #  * `bst build` pushes all build elements ONLY to configured 'push' cache
 #  * `bst pull` finds artifacts that are available only in the secondary cache
 #
diff --git a/tests/frontend/show.py b/tests/frontend/show.py
index 9c32dd664..88f38dd6a 100644
--- a/tests/frontend/show.py
+++ b/tests/frontend/show.py
@@ -45,6 +45,27 @@ def test_show_invalid_element_path(cli, datafiles):
         'show',
         "foo.bst"])
 
+
+@pytest.mark.datafiles(os.path.join(DATA_DIR, 'project_default'))
+def test_show_default(cli, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    result = cli.run(project=project, silent=True, args=[
+        'show'])
+
+    result.assert_success()
+
+    # Get the result output of "[state sha element]" and turn into a list
+    results = result.output.strip().split(" ")
+    expected = 'target2.bst'
+    assert results[2] == expected
+
+
+@pytest.mark.datafiles(os.path.join(DATA_DIR, 'project_fail'))
+def test_show_fail(cli, datafiles):
+    project = os.path.join(datafiles.dirname, datafiles.basename)
+    result = cli.run(project=project, silent=True, args=[
+        'show'])
+
     result.assert_main_error(ErrorDomain.LOAD, LoadErrorReason.INVALID_DATA)