From 194d44746597ef9c745d94cd3befb117544e841c Mon Sep 17 00:00:00 2001
From: Nick Coghlan <ncoghlan@gmail.com>
Date: Oct 27 2017 05:54:46 +0000
Subject: Emit generated modulemd on stdout


Emitting the generated modulemd on stdout is more
useful during development, and the related --output
option gives users full control of the name of the
resulting file (rather than having to be aware of
a fedmod-defined implicit naming convention).

---

diff --git a/README.md b/README.md
index cdca809..ff56937 100644
--- a/README.md
+++ b/README.md
@@ -53,8 +53,10 @@ whichever one you think looks better as your starting point.
 ## Modulemd creation
 
 `fedmod rpm2module [RPM NAMES]` creates a modulemd file from the
-given package names. Output is written as `<input-package-name>.yaml` when a
-single package name is given, and `modulemd-output.yaml` otherwise.
+given package names and emits it on `stdout`. The YAML metadata can be written
+directly to a file instead by passing the ``--output` (or `-o`) option:
+
+    $ fedmod rpm2module -o graphite-web.yaml graphite-web
 
 The following metadata is currently used as input to the draft module generation
 process:
diff --git a/src/_fedmod/cli.py b/src/_fedmod/cli.py
index 514a0f4..f3ec46d 100644
--- a/src/_fedmod/cli.py
+++ b/src/_fedmod/cli.py
@@ -29,6 +29,13 @@ class ModtoolsCLI(object):
             description="Gets package info and dependencies and creates modulemd file."
         )
         parser_rpm2module.add_argument(
+            "--output",
+            "-o",
+            metavar="FILE",
+            dest="output_fname",
+            help="Write to FILE instead of stdout"
+        )
+        parser_rpm2module.add_argument(
             "pkgs",
             metavar='PKGS',
             nargs='+',
@@ -61,7 +68,7 @@ def run():
             logging.basicConfig(level=logging.INFO)
         if cli.args.cmd_name == 'rpm2module':
             mg = ModuleGenerator(cli.args.pkgs)
-            mg.run()
+            mg.run(cli.args.output_fname)
         elif cli.args.cmd_name == 'fetch-metadata':
             _repodata.download_repo_metadata()
 
diff --git a/src/_fedmod/module_generator.py b/src/_fedmod/module_generator.py
index 33836db..9ddda30 100644
--- a/src/_fedmod/module_generator.py
+++ b/src/_fedmod/module_generator.py
@@ -1,5 +1,6 @@
 from __future__ import absolute_import
 
+import sys
 import modulemd
 import logging
 import dnf
@@ -78,10 +79,9 @@ class ModuleGenerator(object):
             raise ValueError('No package found in repo')
         self.pkg = q[0]
 
-    def _save_module_md(self):
+    def _save_module_md(self, output_fname):
         """
-        Function saves modulemd file to the current directory
-        based on argument name
+        Function writes modulemd to either stdout or the given filename
         :return:
         """
 
@@ -89,8 +89,11 @@ class ModuleGenerator(object):
             file_name = self.pkgs[0] + '.yaml'
         else:
             file_name = "modulemd-output.yaml"
-        self.mmd.dump(file_name)
-        print('Modulemd file is generated here ./%s' % file_name)
+        if output_fname is not None:
+            self.mmd.dump(file_name)
+            print('Generated modulemd file: %r' % output_fname)
+        else:
+            print(self.mmd.dumps())
         return True
 
     def _update_module_md(self):
@@ -136,6 +139,7 @@ class ModuleGenerator(object):
             self.mmd.filter.add_rpm(pkg)
 
         # TODO: Emit something for non-empty self.unresolved_build_rpms
+        #       rather than relying solely on the warnings emitted on stderr
 
 
     def _get_build_order(self, pkg):
@@ -144,8 +148,8 @@ class ModuleGenerator(object):
         else:
             return 0
 
-    def run(self):
+    def run(self, output_fname):
         if len(self.pkgs) == 1:
             self._get_pkg_info()
         self._update_module_md()
-        self._save_module_md()
+        self._save_module_md(output_fname)
diff --git a/tests/test_module_generator.py b/tests/test_module_generator.py
index e711b91..d8c7aa8 100644
--- a/tests/test_module_generator.py
+++ b/tests/test_module_generator.py
@@ -8,11 +8,11 @@ def _generate_modulemd(rpms):
     cmd_input.extend(rpms)
     cli = ModtoolsCLI(cmd_input)
     mg = ModuleGenerator(cli.pkgs)
-    mg.run()
     if len(rpms) == 1:
         output_fname = rpms[0] + '.yaml'
     else:
         output_fname = 'modulemd-output.yaml'
+    mg.run(output_fname)
     return mg, output_fname