[PY 3.8] modernize common test fixtures

Apply changes to quiet open-file warnings.  Add docstring to a few.
Switch os.system usage to subprocess.call. Add if-main logic.

Signed-off-by: Mats Wichmann <mats@linux.com>

5 files changed, 83 insertions, 49 deletions

diff --git a/test/fixture/mycompile.py b/test/fixture/mycompile.py
index 555c2c8fa..313e4b52d 100644
--- a/test/fixture/mycompile.py
+++ b/test/fixture/mycompile.py
@@ -1,8 +1,19 @@
+r"""
+Phony "compiler" for testing SCons.
+
+Copies its source files to the target file, dropping lines
+that match a pattern, so we can recognize the tool
+has made a modification.
+"""
+
 import sys
-line = ('/*' + sys.argv[1] + '*/\n').encode()
-outfile = open(sys.argv[2], 'wb')
-for f in sys.argv[3:]:
-    infile = open(f, 'rb')
-    for l in [l for l in infile.readlines() if l != line]:
-        outfile.write(l)
-sys.exit(0)
+
+if __name__ == '__main__':
+    line = '/*' + sys.argv[1] + '*/\n'
+    with open(sys.argv[2], 'w') as ofp:
+        for f in sys.argv[3:]:
+            with open(f, 'r') as ifp:
+                lines = [l for l in ifp.readlines() if l != line]
+                for l in lines:
+                    ofp.write(l)
+    sys.exit(0)
diff --git a/test/fixture/mylink.py b/test/fixture/mylink.py
index 7c03f0078..5006f22f5 100644
--- a/test/fixture/mylink.py
+++ b/test/fixture/mylink.py
@@ -1,31 +1,39 @@
+r"""
+Phony "linker" for testing SCons.
+
+Recognizes the option to specify an output file, ignoring
+all others; copies input lines to the output file except
+ones that contain a pattern, so we can recognize the tool
+has made a modification.
+"""
+
 import sys
 
-if sys.platform == 'win32':
-    args = sys.argv[1:]
-    while args:
-        a = args[0]
-        if a == '-o':
-            out = args[1]
-            args = args[2:]
-            continue
-        if not a[0] in '/-':
-            break
-        args = args[1:]
-        if a[:5].lower() == '/out:': out = a[5:]
-    infile = open(args[0], 'rb')
-    outfile = open(out, 'wb')
-    for l in infile.readlines():
-        if l[:5] != b'#link':
-            outfile.write(l)
-    sys.exit(0)
-else:
-    import getopt
-    opts, args = getopt.getopt(sys.argv[1:], 'o:')
-    for opt, arg in opts:
-        if opt == '-o': out = arg
-    infile = open(args[0], 'rb')
-    outfile = open(out, 'wb')
-    for l in infile.readlines():
-        if l[:5] != b'#link':
-            outfile.write(l)
-    sys.exit(0)
+if __name__ == '__main__':
+    if sys.platform == 'win32':
+        args = sys.argv[1:]
+        while args:
+            a = args[0]
+            if a == '-o':
+                out = args[1]
+                args = args[2:]
+                continue
+            if not a[0] in '/-':
+                break
+            args = args[1:]
+            if a[:5].lower() == '/out:': out = a[5:]
+        with open(args[0], 'r') as ifp, open(out, 'w') as ofp:
+            for l in ifp.readlines():
+                if not l.startswith('#link'):
+                    ofp.write(l)
+        sys.exit(0)
+    else:
+        import getopt
+        opts, args = getopt.getopt(sys.argv[1:], 'o:')
+        for opt, arg in opts:
+            if opt == '-o': out = arg
+        with open(args[0], 'r') as ifp, open(out, 'w') as ofp:
+            for l in ifp.readlines():
+                if not l.startswith('#link'):
+                    ofp.write(l)
+        sys.exit(0)
diff --git a/test/fixture/myrewrite.py b/test/fixture/myrewrite.py
index 40bf830c8..bd90a68c5 100644
--- a/test/fixture/myrewrite.py
+++ b/test/fixture/myrewrite.py
@@ -1,7 +1,16 @@
+r"""
+Phony tool to modify a file in place for testing SCons.
+
+Drops lines that match a pattern.  Currently used to test
+ranlib-related behavior without invoking ranlib.
+"""
+
 import sys
-line = ('/*' + sys.argv[1] + '*/\n').encode()
-lines = open(sys.argv[2], 'rb').readlines()
-outfile = open(sys.argv[2], 'wb')
-for l in [l for l in lines if l != line]:
-    outfile.write(l)
-sys.exit(0)
+
+if __name__ == '__main__':
+    line = ('/*' + sys.argv[1] + '*/\n')
+    with open(sys.argv[2], 'w') as ofp, open(sys.argv[2], 'r') as ifp:
+        lines = [l for l in ifp.readlines() if l != line]
+        for l in lines:
+            ofp.write(l)
+    sys.exit(0)
diff --git a/test/fixture/wrapper.py b/test/fixture/wrapper.py
index f02ea03d3..87913905c 100644
--- a/test/fixture/wrapper.py
+++ b/test/fixture/wrapper.py
@@ -1,6 +1,10 @@
 import os
 import sys
-if '--version' not in sys.argv and '-dumpversion' not in sys.argv:
+import subprocess
+
+if __name__ == '__main__':
     path = os.path.join(os.path.dirname(os.path.relpath(__file__)), 'wrapper.out')
-    open(path, 'wb').write(b"wrapper.py\n")
-os.system(" ".join(sys.argv[1:]))
+    if '--version' not in sys.argv and '-dumpversion' not in sys.argv:
+        with open(path, 'w') as f:
+            f.write("wrapper.py\n")
+    subprocess.call(sys.argv[1:])
diff --git a/test/fixture/wrapper_with_args.py b/test/fixture/wrapper_with_args.py
index fccab729c..f9e4d2210 100644
--- a/test/fixture/wrapper_with_args.py
+++ b/test/fixture/wrapper_with_args.py
@@ -1,7 +1,9 @@
 import os
 import sys
+import subprocess
 
-path = os.path.join(os.path.dirname(os.path.relpath(__file__)), 'wrapper.out')
-
-open(path, 'a').write("wrapper_with_args.py %s\n" % " ".join(sys.argv[1:]))
-os.system(" ".join(sys.argv[1:]))
+if __name__ == '__main__':
+    path = os.path.join(os.path.dirname(os.path.relpath(__file__)), 'wrapper.out')
+    with open(path, 'a') as f:
+        f.write("wrapper_with_args.py %s\n" % " ".join(sys.argv[1:]))
+    subprocess.call(sys.argv[1:])