docs(AutoFSelector): describe what hash and phash cover

The `phash` documentation was copied from `mlr3::Learner`, where the
partial hash excludes the parameter values that are varied during
tuning. The `AutoFSelector` has no such components, so `$phash` is
deliberately identical to `$hash`, as in `mlr3tuning::AutoTuner`.

Author: be-marc

R/AutoFSelector.R

@@ -329,6 +329,8 @@ AutoFSelector = R6Class(
 
     #' @field hash (`character(1)`)\cr
     #' Hash (unique identifier) for this object.
+    #' Covers the id, the parameter values, the predict type, the fallback learner, the parallel predict flag,
+    #' the [FSelector], the arguments of the [FSelectInstanceBatchSingleCrit] and the store fselect instance flag.
     hash = function(rhs) {
       assert_ro_binding(rhs)
       calculate_hash(
@@ -345,9 +347,10 @@ AutoFSelector = R6Class(
     },
 
     #' @field phash (`character(1)`)\cr
-    #' Hash (unique identifier) for this partial object,
-    #' excluding some components which are varied systematically during tuning (parameter values)
-    #' or feature selection (feature names).
+    #' Hash (unique identifier) for this partial object.
+    #' The [AutoFSelector] has no components that are varied systematically during tuning or feature selection,
+    #' because the search space is created internally from the task.
+    #' The partial hash is therefore deliberately identical to `$hash`.
     phash = function(rhs) {
       assert_ro_binding(rhs)
       self$hash

man/AutoFSelector.Rd

@@ -319,3 +319,20 @@ test_that("instantiated resampling with foreign row ids is rejected", {
   expect_error(run("cv", folds = 3), "set 1 of inner resampling 'cv' contains row ids")
   expect_error(run("holdout"), "set 1 of inner resampling 'holdout' contains row ids")
 })
+
+test_that("hash and phash are stable and identical", {
+  at_1 = auto_fselector(
+    fselector = fs("random_search", batch_size = 1),
+    learner = lrn("classif.rpart"),
+    resampling = rsmp("holdout"),
+    measure = msr("classif.ce"),
+    term_evals = 2
+  )
+  at_2 = at_1$clone(deep = TRUE)
+
+  expect_equal(at_1$hash, at_2$hash)
+  expect_equal(at_1$phash, at_1$hash)
+
+  at_2$id = "other"
+  expect_false(at_1$hash == at_2$hash)
+})