fix invalid arg handling (io, stdin) and add tests for this

t/test.sh

@@ -0,0 +1,45 @@
+#!/bin/sh
+
+# simple commandline unit test script
+
+t="../tablizer"
+fail=0
+
+ex() {
+    # execute a test, report+exit on error, stay silent otherwise
+    log="/tmp/test-tablizer.$$.log"
+    name=$1
+    shift
+
+    echo -n "TEST $name "
+
+    $* > $log 2>&1
+
+    if test $? -ne 0; then
+        echo "failed, see $log"
+        fail=1
+    else
+        echo "ok"
+        rm -f $log
+    fi
+}
+
+# only use files in test dir
+cd $(dirname $0)
+
+echo "Executing commandline tests ..."
+
+# io pattern tests
+ex io-pattern-and-file $t bk7 testtable.kube
+cat testtable.kube | ex io-pattern-and-stdin $t bk7
+cat testtable.kube | ex io-pattern-and-stdin-dash $t bk7 -
+
+# same w/o pattern
+ex io-just-file $t testtable.kube
+cat testtable.kube | ex io-just-stdin $t
+cat testtable.kube | ex io-just-stdin-dash $t -
+
+if test $fail -ne 0; then
+    echo "!!! Some tests failed !!!"
+    exit 1
+fi

t/testtable

@@ -0,0 +1,6 @@
+NAME                                                 READY   STATUS    RESTARTS       AGE
+alertmanager-kube-prometheus-alertmanager-0          2/2     Running   35 (45m ago)   11d
+grafana-fcc54cbc9-bk7s8                              1/1     Running   17 (45m ago)   1d
+kube-prometheus-blackbox-exporter-5d85b5d8f4-tskh7   1/1     Running   17 (45m ago)   1h44m
+kube-prometheus-kube-state-metrics-b4cd9487-75p7f    1/1     Running   20 (45m ago)   45m
+kube-prometheus-node-exporter-bfzpl                  1/1     Running   17 (45m ago)   54s