"expects valid input: relations is a named list"
"expects valid input: relation elements correct lengths"
"expects valid input: list elements contain df and keys elements, and no others, correct classes"
"expects valid input: attrs_order is a character"
"expects valid input: no duplicate attrs"
"expects valid input: no duplicate attrs in keys"
"expects valid input: no duplicate attrs_order"
"expects valid input: relation attributes are in attrs_order"
"expects valid input: relation attributes get ordered by key mentions first"
"expects valid input: keys are in columns"
"expects valid input: keys are satisfied"
"expect records name reassignments to result in an error or a valid relation"
"sorts relation key contents attrs_order"
"sorts relation keys according to length and attrs_order"
"sorts relation attributes according to sorted keys and attrs_order"
"is subsetted to a valid relation schema, obeys usual subsetting rules..."
"expects a relation value for subset re-assignment"
"^value must also be a relation object$"
"is made unique with no duplicate schemas"
"concatenates to a valid relation schema"
"is composed of its records(), keys(), names(), and attrs_order()"
"has record attributes given by attrs()"
"relation a: a, b; 1 record\\n  key 1: a"
"can be formatted, e.g. for data.frame entry"

relation: concatenates without losing attribute orderings, if consistent

Falsifiable after 1 tests, and 100 shrinks
<simpleError in expect_all_true(mapply(identical, lapply(lst, attrs_order), lapply(lst,     function(x) intersect(attrs_order(res), attrs_order(x))))): could not find function "expect_all_true">
Counterexample:
[[1]]
0 relations
0 attributes

[[2]]
0 relations
4 attributes: b, c, d, e

Falsifiable after 1 tests, and 2 shrinks
<simpleError in expect_all_true(mapply(identical, lapply(lst, attrs_order), lapply(lst,     function(x) intersect(attrs_order(res), attrs_order(x))))): could not find function "expect_all_true">
Counterexample:
[[1]]
0 relation schemas
1 attribute: e

[[2]]
0 relation schemas
1 attribute: e