DATAREDIS-1013 - Polishing.

Add test. Consider grammar depending on argument count.

Original pull request: #468.

Author: mp911de

src/main/java/org/springframework/data/redis/core/RedisCommand.java

@@ -342,21 +342,25 @@ public void validateArgumentCount(int nrArguments) {
 			if (requiresExactNumberOfArguments()) {
 				if (nrArguments != maxArgs) {
 					throw new IllegalArgumentException(
-							String.format("%s command requires %s arguments.", this.name(), this.maxArgs));
+							String.format("%s command requires %s %s.", this.name(), this.maxArgs, arguments(this.maxArgs)));
 				}
 			}
 			if (nrArguments < minArgs) {
 				throw new IllegalArgumentException(
-						String.format("%s command requires at least %s arguments.", this.name(), this.minArgs));
+						String.format("%s command requires at least %s %s.", this.name(), this.minArgs, arguments(this.maxArgs)));
 			}
 
 			if (maxArgs > 0 && nrArguments > maxArgs) {
 				throw new IllegalArgumentException(
-						String.format("%s command requires at most %s arguments.", this.name(), this.maxArgs));
+						String.format("%s command requires at most %s %s.", this.name(), this.maxArgs, arguments(this.maxArgs)));
 			}
 		}
 	}
 
+	private static String arguments(int count) {
+		return count == 1 ? "argument" : "arguments";
+	}
+
 	/**
 	 * Returns the command represented by the given {@code key}. Returns {@link #UNKNOWN} if no matching command could be
 	 * found.

src/test/java/org/springframework/data/redis/core/RedisCommandUnitTests.java

@@ -64,14 +64,15 @@ public void shouldReturnUnknownCommandForUnknownCommandString() {
 		assertThat(RedisCommand.failsafeCommandLookup("strangecommand"), is(RedisCommand.UNKNOWN));
 	}
 
-	@Test // DATAREDIS-73, DATAREDIS-972
+	@Test // DATAREDIS-73, DATAREDIS-972, DATAREDIS-1013
 	public void shouldNotThrowExceptionOnValidArgumentCount() {
 
 		RedisCommand.AUTH.validateArgumentCount(1);
 		RedisCommand.ZADD.validateArgumentCount(3);
 		RedisCommand.ZADD.validateArgumentCount(4);
 		RedisCommand.ZADD.validateArgumentCount(5);
 		RedisCommand.ZADD.validateArgumentCount(100);
+		RedisCommand.SELECT.validateArgumentCount(1);
 	}
 
 	@Test // DATAREDIS-822
@@ -86,16 +87,16 @@ public void shouldConsiderMinMaxArguments() {
 	public void shouldReportArgumentMismatchIfMaxArgumentsExceeded() {
 
 		expectedException.expect(IllegalArgumentException.class);
-		expectedException.expectMessage("BITPOS command requires at most 4 arguments");
+		expectedException.expectMessage("SELECT command requires 1 argument");
 
-		RedisCommand.BITPOS.validateArgumentCount(5);
+		RedisCommand.SELECT.validateArgumentCount(0);
 	}
 
 	@Test // DATAREDIS-73
 	public void shouldThrowExceptionOnInvalidArgumentCountWhenExpectedExactMatch() {
 
 		expectedException.expect(IllegalArgumentException.class);
-		expectedException.expectMessage("AUTH command requires 1 arguments");
+		expectedException.expectMessage("AUTH command requires 1 argument");
 
 		RedisCommand.AUTH.validateArgumentCount(2);
 	}
@@ -104,7 +105,7 @@ public void shouldThrowExceptionOnInvalidArgumentCountWhenExpectedExactMatch() {
 	public void shouldThrowExceptionOnInvalidArgumentCountForDelWhenExpectedMinimalMatch() {
 
 		expectedException.expect(IllegalArgumentException.class);
-		expectedException.expectMessage("DEL command requires at least 1 arguments");
+		expectedException.expectMessage("DEL command requires at least 1 argument");
 
 		RedisCommand.DEL.validateArgumentCount(0);
 	}