From eef7b40a392750d9ff86280a64fb0b64f80a4b7e Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Sat, 13 Feb 2021 09:04:20 +0200
Subject: feat: allow subplot.md to be used to test an installed Subplot

---
 subplot.md | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 subplot.py | 41 +++++++++++++++++++++++++++--------------
 2 files changed, 75 insertions(+), 14 deletions(-)

diff --git a/subplot.md b/subplot.md
index d701995..2db50f6 100644
--- a/subplot.md
+++ b/subplot.md
@@ -213,6 +213,54 @@ be good and helpful, writing it will require effort and skill. No tool
 can replace that.
 
 
+
+## Using this document to verify Subplot works
+
+This document ("subplot") can be used to verify Subplot itself from
+its source tree or an installed Subplot. The default is to test
+Subplot from the source tree, and the `./check` script does that. You
+can run this in the source tree to build Subplot and then verify it
+using itself:
+
+~~~sh
+$ cargo build -q
+$ cargo run --bin sp-codegen -- subplot.md -o test.py
+$ python3 test.py
+... much output
+OK, all scenarios finished successfully
+$ 
+~~~
+
+To test an installed Subplot, generate the test program, and tell the
+test program where Subplot is installed. Again, in the Subplot source
+tree:
+
+~~~sh
+$ cargo build -q
+$ cargo run --bin sp-codegen -- subplot.md -o test.py
+$ python3 test.py  --env SUBPLOT_DIR=/usr/local/bin
+... much output
+OK, all scenarios finished successfully
+$ 
+~~~
+
+You can do this with an installed Subplot as well:
+
+~~~sh
+$ cargo clean
+$ /usr/local/bin/sp-codegen subplot.md -o test.py
+$ python3 test.py --env SUBPLOT_DIR=/usr/local/bin
+... much output
+OK, all scenarios finished successfully
+$
+~~~
+
+The generated test program is self-standing, and can be run from
+anywhere. However, to generate it you need to be in the Subplot
+source tree. You can move it elsewhere after generating it, you if you
+prefer.
+
+
 # Requirements
 
 This chapter lists requirements for Subplot. These requirements are
diff --git a/subplot.py b/subplot.py
index 7d9544b..975b579 100644
--- a/subplot.py
+++ b/subplot.py
@@ -20,23 +20,36 @@ def install_subplot(ctx):
     runcmd_prepend_to_path = globals()["runcmd_prepend_to_path"]
     srcdir = globals()["srcdir"]
 
-    # Create a "bin" directory for the wrapper. Can't put this into datadir, as
-    # some of Subplot's scenarios make assumptions on what files exist there.
-    bindir = ctx["bin-dir"] = tempfile.mkdtemp()
-    for prog in ["sp-codegen", "sp-docgen"]:
-        filename = os.path.join(bindir, prog)
-        with open(filename, "w") as f:
-            f.write(wrapper.format(prog=prog, srcdir=srcdir))
-        os.chmod(filename, 0o755)
-
-    # Add the temporary bin directory to the path, and then the source
-    # directory's Rust binary target directory.
-    runcmd_prepend_to_path(ctx, dirname=bindir)
-    runcmd_prepend_to_path(ctx, dirname=os.path.join(srcdir, "target", "debug"))
+    # If the SUBPLOT_DIR is set, we expect the Subplot binaries to be installed
+    # in that directory. Otherwise, we expect them to be in the source
+    # directory, under target/debug, which is where Rust puts them. In the
+    # latter case, we create a wrapper script to add the necessary options to
+    # also use the resources from the source tree.
+
+    bindir = os.environ.get("SUBPLOT_DIR")
+    if bindir is not None:
+        runcmd_prepend_to_path(ctx, dirname=bindir)
+    else:
+        # Create a "bin" directory for the wrapper. Can't put this into datadir, as
+        # some of Subplot's scenarios make assumptions on what files exist there.
+        bindir = ctx["bin-dir"] = tempfile.mkdtemp()
+        for prog in ["sp-codegen", "sp-docgen"]:
+            filename = os.path.join(bindir, prog)
+            with open(filename, "w") as f:
+                f.write(wrapper.format(prog=prog, srcdir=srcdir))
+            os.chmod(filename, 0o755)
+
+        # Add the temporary bin directory to the path, and then the source
+        # directory's Rust binary target directory.
+        runcmd_prepend_to_path(ctx, dirname=bindir)
+        runcmd_prepend_to_path(ctx, dirname=os.path.join(srcdir, "target", "debug"))
 
 
 def uninstall_subplot(ctx):
-    shutil.rmtree(ctx["bin-dir"])
+    if "bin-dir" in ctx:
+        bindir = ctx["bin-dir"]
+        if os.path.exists(bindir):
+            shutil.rmtree(bindir)
 
 
 def scenario_was_run(ctx, name=None):
-- 
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