d minimum vararg

Author: actions-user

approvaltests-util-tests/src/test/java/com/spun/util/MinimumVarargSamples.java

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+package com.spun.util;
+
+import org.junit.jupiter.api.Test;
+
+public class MinimumVarargSamples
+{
+  @Test
+  void testCompilation()
+  {
+    // begin-snippet: minimalVarargsException
+    int smallest = findSmallest();
+    // end-snippet
+  }
+  // begin-snippet: minimalVarargsRuntime
+  public Integer findSmallest(Integer... numbers)
+  {
+    if (numbers == null || numbers.length < 1)
+    { throw new IllegalArgumentException("you must have at least one number"); }
+    // rest of the code
+    // end-snippet
+    return 42;
+  }
+  // begin-snippet: minimalVarargsCompileTime
+  public Integer findSmallest(Integer first, Integer... numbers)
+  {
+    Integer[] combined = ArrayUtils.combine(first, numbers);
+    // rest of the code
+    // end-snippet
+    return 42;
+  }
+}

approvaltests-util/docs/how_to/VarArgsWithAtleastOne.md

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+<a id="top"></a>
+
+# How to create non-empty arrays with var args
+
+toc
+
+## The problem
+
+Let's say you want to accept a variable amount of arguments, but you have a minimum of one that is required.
+Most solutions for this occur at runtime. Of course, it would be better if they occurred at compile time.
+
+### Runtime solution
+
+snippet: minimalVarargsRuntime
+
+### Compile time solution
+
+An easy way to deal with this is force the first parameter by declaring it explicitly.
+If you do this, you will want to recombine this array almost immediately `ArrayUtils.combine(T, T...)` is an elegant way to do this.
+Please be aware that it will not work with primitives.
+
+snippet: minimalVarargsCompileTime
+
+### Advantages
+
+If you use the runtime solution, the following will compile but throw an error when you run it.  
+If you use the compile time solution, it will not compile.
+
+snippet: minimalVarargsException
+
+### Where to use this
+
+Even though this only adds a small amount of complexity, we don't tend to use it for methods that are only called internally.
+However, it is highly suggested if you have a public facing method.
+
+Following the philosophy of [poka-yoke](https://en.wikipedia.org/wiki/Poka-yoke) or mistake proofing.