test/cases: disregard ordering in "strings/concat: set" test

Since anything can happen, we now list the possibilities (3! = 6),
and check that any of them was the result.

Fixes #2924.

Signed-off-by: Stephan Renatus <stephan.renatus@gmail.com>

internal/wasm/sdk/test/e2e/exceptions.yaml

@@ -1,6 +1,5 @@
 # Exception Format is <test name>: <reason>
 "baseandvirtualdocs/base/virtual: conflicts": "document merge conflict - https://github.com/open-policy-agent/opa/issues/2926"
-"strings/concat: set": "test result order is not consistent - https://github.com/open-policy-agent/opa/issues/2924"
 "strings/format_int": "rounding error - https://github.com/open-policy-agent/opa/issues/2923"
 "strings/format_int: ref dest": "rounding error - https://github.com/open-policy-agent/opa/issues/2923"
 "strings/format_int: ref dest (2)": "rounding error - https://github.com/open-policy-agent/opa/issues/2923"

test/cases/testdata/strings/test-strings-0883.yaml

@@ -1,95 +1,25 @@
 cases:
 - data:
-    a:
-    - 1
-    - 2
-    - 3
-    - 4
-    b:
-      v1: hello
-      v2: goodbye
-    c:
-    - x:
-      - true
-      - false
-      - foo
-      "y":
-      - null
-      - 3.14159
-      z:
-        p: true
-        q: false
-    d:
-      e:
-      - bar
-      - baz
-    f:
-    - xs:
-      - 1
-      ys:
-      - 2
-    - xs:
-      - 2
-      ys:
-      - 3
-    g:
-      a:
-      - 1
-      - 0
-      - 0
-      - 0
-      b:
-      - 0
-      - 2
-      - 0
-      - 0
-      c:
-      - 0
-      - 0
-      - 0
-      - 4
-    h:
-    - - 1
-      - 2
-      - 3
-    - - 2
-      - 3
-      - 4
-    l:
-    - a: bob
-      b: -1
-      c:
-      - 1
-      - 2
-      - 3
-      - 4
-    - a: alice
-      b: 1
-      c:
-      - 2
-      - 3
-      - 4
-      - 5
-      d: null
-    m: []
-    numbers:
-    - "1"
-    - "2"
-    - "3"
-    - "4"
-    strings:
-      bar: 2
-      baz: 3
-      foo: 1
-    three: 3
   modules:
   - |
-    package generated
+    package test
 
-    p = x {
-      concat(",", {"1", "2", "3"}, x)
+    # Sets are unordered, so the output is not guaranteed.
+    # These are theoretically possible:
+    possibilities = {
+      "1,2,3",
+      "2,3,1",
+      "3,1,2",
+      "3,2,1",
+      "2,1,3",
+      "1,3,2"
+    }
+
+    p {
+      x := concat(",", {"1", "2", "3"})
+      possibilities[x]
     }
   note: 'strings/concat: set'
-  query: data.generated.p = x
+  query: data.test.p = x
   want_result:
-  - x: 1,2,3
+  - x: true