rewrite prop_relPathDirToFileAbs_basics

This was not a good test, it broke the requirement that
relPathDirToFileAbs take absolute paths. And it failed when the two
input paths were eg, the same but differently normalized.

Replaced with some tests of the real basics of that function.

Utility/Path.hs

@@ -189,8 +189,7 @@ splitShortExtensions' maxextension = go []
 		(base, ext) = splitExtension f
 		len = B.length ext
 
-{- This requires the first path to be absolute, and the
- - second path cannot contain ../ or ./
+{- This requires both paths to be absolute and normalized.
  -
  - On Windows, if the paths are on different drives,
  - a relative path is not possible and the path is simply

Utility/Path/Tests.hs

@@ -35,16 +35,14 @@ prop_upFrom_basics tdir
 	p = fromRawFilePath <$> upFrom (toRawFilePath dir)
 	dir = fromTestableFilePath tdir
 
-prop_relPathDirToFileAbs_basics :: TestableFilePath -> TestableFilePath -> Bool
-prop_relPathDirToFileAbs_basics fromt tot
-	| from == to = null r
-	| otherwise = not (null r)
+prop_relPathDirToFileAbs_basics :: TestableFilePath -> Bool
+prop_relPathDirToFileAbs_basics pt = and
+	[ relPathDirToFileAbs p (p </> "bar") == "bar"
+	, relPathDirToFileAbs (p </> "bar") p == ".."
+	, relPathDirToFileAbs p p == ""
+	]
   where
-	from = fromTestableFilePath fromt
-	to = fromTestableFilePath tot
-	r = fromRawFilePath $ relPathDirToFileAbs
-		(toRawFilePath from)
-		(toRawFilePath to)
+	p = pathSeparator `B.cons` toRawFilePath (fromTestableFilePath pt)
 
 prop_relPathDirToFileAbs_regressionTest :: Bool
 prop_relPathDirToFileAbs_regressionTest = same_dir_shortcurcuits_at_difference

doc/bugs/prop__95__relPathDirToFileAbs__95__basics_fail_on_crippled___126__.mdwn

@@ -14,3 +14,5 @@ Fresh build of 8.20201129+git100-g2d84bf992-1~ndall+1 when having HOME (base sys
 
 [[!meta author=yoh]]
 [[!tag projects/datalad]]
+
+> [[fixed|done]] --[[Joey]]

doc/bugs/prop__95__relPathDirToFileAbs__95__basics_fail_on_crippled___126__/comment_1_23bf4756af808d1b2cf89f7da119031f._comment

@@ -0,0 +1,11 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2021-01-13T17:01:07Z"
+ content="""
+This is a pure test, and the filesystem does not affect it in any way.
+
+The test is slightly broken, in that when two paths
+are the same except slightly differently normalized (eg, "A" vs "A/"),
+it fails. Really not a great test overall, rewriting.
+"""]]