Process output with jq, pretty print, and return bad retcode on failures

tests/run-tests.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 #
 # Our little test runner.
-#
+
 set -euo pipefail
 
 cd "$(dirname "$0")"
@@ -12,8 +12,77 @@ if [[ "$#" -eq 1 ]]; then
     extra_flags="-A $1"
 fi
 
-
 # Need to build first or the store paths don't exist
 # for default.nix to traverse
 nix-build &>/dev/null
-nix-instantiate --eval --strict --json $extra_flags
+results="$(nix-instantiate --eval --strict --json $extra_flags)"
+
+# Normalize input before handing it over to jq
+if [[ -n "$extra_flags" ]] && [[ "${1::1}" != "@" ]]; then
+    results="{ \"$1\": $results }"
+fi
+
+# Parse and format the results with jq
+#
+# This expects the JSON format to look like:
+#     { "test-case-name": [ { "path": "./path/to/file", "status": "missing" } ] }
+#
+# There is a special case ("@onlyFailures") which is a key with
+# the expected format nested inside of it. In order to not choke
+# on this "report" style of key, we filter out keys starting with
+# "@".
+result_string=$(
+    echo "$results" |\
+        jq -r '
+            "\\e[0;91m" as $red |
+            "\\e[0;92m" as $green |
+            "\\e[0m" as $reset |
+            to_entries |
+            map(select(.key|startswith("@") == false)) |
+                (
+                    map(
+                        (.value|length) as $errors |
+                        "TEST: " + .key + " " +
+                        (
+                            if $errors > 0
+                            then $red + "(" + ($errors|tostring) + " errors"
+                            else $green + "(SUCCESS" end
+                        ) +
+                        ")" + $reset + "\n" +
+                        ( .value |
+                            map(
+                                "  " +
+                                (
+                                    if .status == "missing"
+                                    then "MISSING "
+                                    else "EXTRA   " end
+                                ) +
+                                .path + "\n"
+                            ) | add
+                        )
+                    )|.[]
+                ),
+                (
+                    [ (map(select(.value|length > 0))|length)
+                    , (map(select(.value|length == 0))|length)
+                    ] |
+                    "Tests completed. " +
+                    (
+                        if .[1] > 0
+                        then $green + (.[1]|tostring) + " succeeded" + $reset + ". "
+                        else "" end
+                    ) +
+                    (
+                        if .[0] > 0
+                        then $red + (.[0]|tostring) + " failed" + $reset + "."
+                        else "" end
+                    )
+                )'
+)
+
+echo -e "$result_string"
+
+# If there are errors in the output, return a non-zero exit code
+if grep -Po "^TEST:.*?\(\d+ errors\)" <<< "$result_string" &>/dev/null; then
+    exit 1
+fi