integration: test more copy edge-cases

The existing archive implementation is not easy to reason about by
reading the source. Prepare to rewrite it by covering more edge cases in
tests. The new test cases were determined by black-box characterizing
the existing behaviour.

Signed-off-by: Cory Snider <csnider@mirantis.com>

integration/container/copy_test.go

@@ -158,16 +158,23 @@ func TestCopyFromContainer(t *testing.T) {
 		expect map[string]string
 	}{
 		{"/", map[string]string{"/": "", "/foo": "hello", "/bar/quux/baz": "world", "/bar/filesymlink": "", "/bar/dirsymlink": "", "/bar/notarget": ""}},
+		{".", map[string]string{"./": "", "./foo": "hello", "./bar/quux/baz": "world", "./bar/filesymlink": "", "./bar/dirsymlink": "", "./bar/notarget": ""}},
+		{"/.", map[string]string{"./": "", "./foo": "hello", "./bar/quux/baz": "world", "./bar/filesymlink": "", "./bar/dirsymlink": "", "./bar/notarget": ""}},
+		{"./", map[string]string{"./": "", "./foo": "hello", "./bar/quux/baz": "world", "./bar/filesymlink": "", "./bar/dirsymlink": "", "./bar/notarget": ""}},
+		{"/./", map[string]string{"./": "", "./foo": "hello", "./bar/quux/baz": "world", "./bar/filesymlink": "", "./bar/dirsymlink": "", "./bar/notarget": ""}},
 		{"/bar/root", map[string]string{"root": ""}},
 		{"/bar/root/", map[string]string{"root/": "", "root/foo": "hello", "root/bar/quux/baz": "world", "root/bar/filesymlink": "", "root/bar/dirsymlink": "", "root/bar/notarget": ""}},
+		{"/bar/root/.", map[string]string{"./": "", "./foo": "hello", "./bar/quux/baz": "world", "./bar/filesymlink": "", "./bar/dirsymlink": "", "./bar/notarget": ""}},
 
 		{"bar/quux", map[string]string{"quux/": "", "quux/baz": "world"}},
 		{"bar/quux/", map[string]string{"quux/": "", "quux/baz": "world"}},
+		{"bar/quux/.", map[string]string{"./": "", "./baz": "world"}},
 		{"bar/quux/baz", map[string]string{"baz": "world"}},
 
 		{"bar/filesymlink", map[string]string{"filesymlink": ""}},
 		{"bar/dirsymlink", map[string]string{"dirsymlink": ""}},
 		{"bar/dirsymlink/", map[string]string{"dirsymlink/": "", "dirsymlink/baz": "world"}},
+		{"bar/dirsymlink/.", map[string]string{"./": "", "./baz": "world"}},
 		{"bar/notarget", map[string]string{"notarget": ""}},
 	} {
 		t.Run(x.src, func(t *testing.T) {