Add "contextual" output option

This is mainly for developer or power-user cases, where one wants to look at
some data for investigation or debugging.  In such cases, it's common for the
set of prefixes to be implicitly known (because they are baked in to the
application, for example), so printing them just produces a large amount of
redundant noise.

That said, it can also be useful programmatically, because it allows several
snippets to be written independently and ultimately concatenated (with a header
to define the prefixes) without redundancy.

2 files changed, 62 insertions, 0 deletions

diff --git a/test/meson.build b/test/meson.build
index 1f736afc..6bb0e033 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -19,6 +19,7 @@ simple_script_paths = [
   'run_filter_suite.py',
   'run_suite.py',
   'test_base.py',
+  'test_contextual.py',
   'test_empty.py',
   'test_multifile.py',
   'test_patterns.py',
@@ -446,6 +447,16 @@ if is_variable('serd_pipe')
       suite: 'io',
     )
   endif
+
+  # Write options
+
+  test(
+    'contextual',
+    files('test_contextual.py'),
+    args: pipe_script_args + files('../serd.ttl'),
+    env: test_env,
+    suite: ['tools', 'pipe', 'output'],
+  )
 endif
 
 # Test specifics to serd-filter
diff --git a/test/test_contextual.py b/test/test_contextual.py
new file mode 100755
index 00000000..6a584c5b
--- /dev/null
+++ b/test/test_contextual.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+
+# Copyright 2022 David Robillard <d@drobilla.net>
+# SPDX-License-Identifier: ISC
+
+"""Test writing with -O contextual (SERD_WRITE_CONTEXTUAL)."""
+
+# pylint: disable=consider-using-f-string
+
+import argparse
+import sys
+import shlex
+import subprocess
+import tempfile
+
+parser = argparse.ArgumentParser(description=__doc__)
+
+parser.add_argument("--tool", default="tools/serd-pipe", help="executable")
+parser.add_argument("--wrapper", default="", help="executable wrapper")
+parser.add_argument("input", default="", help="input file")
+
+args = parser.parse_args(sys.argv[1:])
+command = shlex.split(args.wrapper) + [
+    args.tool,
+    "-O",
+    "turtle",
+    "-O",
+    "contextual",
+    args.input,
+]
+
+DOC = "<{0}s> <{0}p> <{0}o> .".format("http://example.org/")
+
+with tempfile.TemporaryFile() as out:
+    proc = subprocess.run(
+        command,
+        check=False,
+        encoding="utf-8",
+        input=DOC,
+        stdout=out,
+        stderr=subprocess.PIPE,
+    )
+
+    assert proc.returncode == 0
+    assert args.wrapper or len(proc.stderr) == 0
+
+    out.seek(0)
+    lines = out.readlines()
+
+    for line in lines:
+        assert "@prefix" not in line.decode("utf-8")