handle 'git' not being installed (#90)

Fixes #89

tests/test_all.py

@@ -1,5 +1,6 @@
 import json
 import math
+import os
 from pathlib import Path
 import platform
 import subprocess
@@ -963,3 +964,27 @@ def test_jit_compile(model_name: str, weights_name: str):
             "JIT-compiled model was SLOWER than original: "
             f"jit={time_yesjit:0.3f} vs nojit={time_nojit:0.3f}"
         )
+
+
+def test_issue_89():
+    from wsinfer.cli.infer import _get_info_for_save
+
+    w = get_model_weights("resnet34", "TCGA-BRCA-v1")
+    d = _get_info_for_save(w)
+    assert d
+    assert "git" in d["runtime"]
+    assert d["runtime"]["git"]
+    assert d["runtime"]["git"]["git_remote"]
+    assert d["runtime"]["git"]["git_branch"]
+
+    # Test that _get_info_for_save does not fail if git is not found.
+    orig_path = os.environ["PATH"]
+    try:
+        os.environ["PATH"] = ""
+        w = get_model_weights("resnet34", "TCGA-BRCA-v1")
+        d = _get_info_for_save(w)
+        assert d
+        assert "git" in d["runtime"]
+        assert d["runtime"]["git"] is None
+    finally:
+        os.environ["PATH"] = orig_path  # reset path

wsinfer/cli/infer.py

@@ -5,6 +5,7 @@
 import os
 from pathlib import Path
 import platform
+import shutil
 import subprocess
 import sys
 import typing
@@ -121,17 +122,20 @@ def get_stdout(args) -> str:
         }
 
     # Test if we are in a git repo. If we are, then get git info.
-    cmd = subprocess.run(
-        "git branch".split(),
-        cwd=here,
-        stdout=subprocess.DEVNULL,
-        stderr=subprocess.DEVNULL,
-    )
-    if cmd.returncode == 0:
+    git_program = shutil.which("git")
+    git_installed = git_program is not None
+    is_git_repo = False
+    if git_installed:
+        cmd = subprocess.run(
+            [str(git_program), "branch"],
+            cwd=here,
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        )
+        is_git_repo = cmd.returncode == 0
+    git_info = None
+    if git_installed and is_git_repo:
         git_info = get_git_info()
-    else:
-        git_info = None
-    del cmd, here  # For sanity.
 
     weights_file = weights.file
     if weights_file is None: