Provide meaningful message for empty environment installs (#28031)

* Provide a meaningful failure message for installation of an empty environment

* Allow regenerating view per offline discussion

2 files changed, 26 insertions, 9 deletions

diff --git a/lib/spack/spack/cmd/install.py b/lib/spack/spack/cmd/install.py
index 95b195bc53..f4a4644312 100644
--- a/lib/spack/spack/cmd/install.py
+++ b/lib/spack/spack/cmd/install.py
@@ -348,17 +348,22 @@ environment variables:
                     env.write(regenerate=False)
 
             specs = env.all_specs()
-            if not args.log_file and not reporter.filename:
-                reporter.filename = default_log_file(specs[0])
-            reporter.specs = specs
+            if specs:
+                if not args.log_file and not reporter.filename:
+                    reporter.filename = default_log_file(specs[0])
+                reporter.specs = specs
 
-            # Tell the monitor about the specs
-            if args.use_monitor and specs:
-                monitor.new_configuration(specs)
+                # Tell the monitor about the specs
+                if args.use_monitor and specs:
+                    monitor.new_configuration(specs)
 
-            tty.msg("Installing environment {0}".format(env.name))
-            with reporter('build'):
-                env.install_all(**kwargs)
+                tty.msg("Installing environment {0}".format(env.name))
+                with reporter('build'):
+                    env.install_all(**kwargs)
+
+            else:
+                msg = '{0} environment has no specs to install'.format(env.name)
+                tty.msg(msg)
 
             tty.debug("Regenerating environment views for {0}"
                       .format(env.name))
diff --git a/lib/spack/spack/test/cmd/install.py b/lib/spack/spack/test/cmd/install.py
index 4fa022d168..2c79880088 100644
--- a/lib/spack/spack/test/cmd/install.py
+++ b/lib/spack/spack/test/cmd/install.py
@@ -1099,3 +1099,15 @@ def test_install_env_with_tests_root(tmpdir, mock_packages, mock_fetch,
         add('depb')
         install('--test', 'root')
         assert not os.path.exists(test_dep.prefix)
+
+
+def test_install_empty_env(tmpdir, mock_packages, mock_fetch,
+                           install_mockery, mutable_mock_env_path):
+    env_name = 'empty'
+    env('create', env_name)
+    with ev.read(env_name):
+        out = install(fail_on_error=False)
+
+    assert env_name in out
+    assert 'environment' in out
+    assert 'no specs to install' in out