Rewrite groovy test as a junit test

cdm/core/src/test/java/ucar/nc2/iosp/netcdf3/TestN3iosp.java

@@ -0,0 +1,56 @@
+package ucar.nc2.iosp.netcdf3;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import org.junit.Test;
+
+public class TestN3iosp {
+
+  @Test
+  public void shouldReturnInvalidForNullOrEmptyNames() {
+    assertThat(N3iosp.isValidNetcdfObjectName(null)).isFalse();
+    assertThrows(NullPointerException.class, () -> N3iosp.makeValidNetcdfObjectName(null));
+
+    assertThat(N3iosp.isValidNetcdfObjectName("")).isFalse();
+    IllegalArgumentException e =
+        assertThrows(IllegalArgumentException.class, () -> N3iosp.makeValidNetcdfObjectName(""));
+    assertThat(e.getMessage()).isEqualTo("Illegal NetCDF object name: ''");
+  }
+
+  @Test
+  public void shouldReturnInvalidForBadFirstCharacters() {
+    // names with first chars not in ([a-zA-Z0-9_]|{UTF8}) are invalid
+    assertThat(N3iosp.isValidNetcdfObjectName(" blah")).isFalse();
+    assertThat(N3iosp.makeValidNetcdfObjectName(" blah")).isEqualTo("blah");
+
+    assertThat(N3iosp.isValidNetcdfObjectName("\n/blah")).isFalse();
+    assertThat(N3iosp.makeValidNetcdfObjectName("\n/blah")).isEqualTo("blah");
+
+    // Unit separator and DEL
+    assertThat(N3iosp.isValidNetcdfObjectName("\u001F\u007F blah")).isFalse();
+    assertThat(N3iosp.makeValidNetcdfObjectName("\u001F\u007F blah")).isEqualTo("blah");
+  }
+
+  @Test
+  public void shouldReturnInvalidForBadCharacters() {
+    // names with remaining chars not in ([^\x00-\x1F\x7F/]|{UTF8})* are invalid
+    assertThat(N3iosp.isValidNetcdfObjectName("1\u000F2\u007F3/4")).isFalse();
+    assertThat(N3iosp.makeValidNetcdfObjectName("1\u000F2\u007F3/4")).isEqualTo("1234");
+
+    // names may not have trailing spaces
+    assertThat(N3iosp.isValidNetcdfObjectName("foo     ")).isFalse();
+    assertThat(N3iosp.makeValidNetcdfObjectName("foo     ")).isEqualTo("foo");
+  }
+
+  @Test
+  public void shouldAcceptValidNames() {
+    // valid names have syntax: ([a-zA-Z0-9_]|{UTF8})([^\x00-\x1F\x7F/]|{UTF8})*
+    assertThat(N3iosp.isValidNetcdfObjectName("_KfS9Jn_s9__")).isTrue();
+    assertThat(N3iosp.makeValidNetcdfObjectName("_KfS9Jn_s9__")).isEqualTo("_KfS9Jn_s9__");
+
+    // unicode characters greater than 0x7F can appear anywhere
+    assertThat(N3iosp.isValidNetcdfObjectName("\u0123\u1234\u2345\u3456")).isTrue();
+    assertThat(N3iosp.makeValidNetcdfObjectName("\u0123\u1234\u2345\u3456")).isEqualTo("\u0123\u1234\u2345\u3456");
+  }
+}