whenFit() and Expect.it()

eo-runtime/src/main/java/EOorg/EOeolang/EOnumber$EOtimes.java

@@ -33,6 +33,7 @@
 import org.eolang.Attr;
 import org.eolang.Data;
 import org.eolang.Dataized;
+import org.eolang.Expect;
 import org.eolang.PhDefault;
 import org.eolang.Phi;
 import org.eolang.Versionized;
@@ -58,9 +59,11 @@ public final class EOnumber$EOtimes extends PhDefault implements Atom {
 
     @Override
     public Phi lambda() {
-        return new Data.ToPhi(
-            new Dataized(this.take(Attr.RHO)).asNumber()
-                * new Dataized(this.take("x")).asNumber()
-        );
+        final Double left = new Dataized(this.take(Attr.RHO)).asNumber();
+        final Double right = new Expect<>(
+            () -> new Dataized(this.take("x")).asNumber(),
+            "number.times expects its second argument to be a number"
+        ).it();
+        return new Data.ToPhi(left * right);
     }
 }

eo-runtime/src/main/java/EOorg/EOeolang/EOtxt/EOsprintf.java

@@ -40,6 +40,7 @@
 import org.eolang.Data;
 import org.eolang.Dataized;
 import org.eolang.ExFailure;
+import org.eolang.Expect;
 import org.eolang.PhDefault;
 import org.eolang.Phi;
 import org.eolang.XmirObject;
@@ -83,8 +84,14 @@ public EOsprintf() {
     public Phi lambda() throws Exception {
         final String format = new Dataized(this.take("format")).asString();
         final Phi args = this.take("args");
-        final Phi retriever = args.take("at");
-        final long length = new Dataized(args.take("length")).asNumber().longValue();
+        final Phi retriever = new Expect<>(
+            () -> args.take("at"),
+            "sprintf expects its second argument to be a tuple with the 'at' attribute"
+        ).it();
+        final long length = new Expect<>(
+            () -> new Dataized(args.take("length")).asNumber().longValue(),
+            "sprintf expects its second argument to be a tuple with the 'length' attribute"
+        ).it();
         final List<Object> arguments = new ArrayList<>(0);
         String pattern = format;
         long index = 0;

eo-runtime/src/main/java/org/eolang/BytesRaw.java

@@ -164,20 +164,19 @@ public <T extends Number> T asNumber(final Class<T> type) {
         final byte[] ret = this.take();
         final Object res;
         final ByteBuffer buf = ByteBuffer.wrap(ret);
-        if (Long.class.equals(type) && ret.length == Long.BYTES) {
-            res = buf.getLong();
-        } else if (Integer.class.equals(type) && ret.length == Integer.BYTES) {
-            res = buf.getInt();
-        } else if (Double.class.equals(type) && ret.length == Double.BYTES) {
-            res = buf.getDouble();
-        } else if (Short.class.equals(type) && ret.length == Short.BYTES) {
-            res = buf.getShort();
+        if (Long.class.equals(type)) {
+            res = BytesRaw.whenFit(buf, ret, Long.class).getLong();
+        } else if (Integer.class.equals(type)) {
+            res = BytesRaw.whenFit(buf, ret, Integer.class).getInt();
+        } else if (Double.class.equals(type)) {
+            res = BytesRaw.whenFit(buf, ret, Double.class).getDouble();
+        } else if (Short.class.equals(type)) {
+            res = BytesRaw.whenFit(buf, ret, Short.class).getShort();
         } else {
             throw new UnsupportedOperationException(
                 String.format(
-                    "Unsupported conversion to \"%s\" for %d bytes",
-                    type,
-                    ret.length
+                    "Can't convert %d bytes to \"%s\"",
+                    ret.length, type.getCanonicalName()
                 )
             );
         }
@@ -253,4 +252,30 @@ private static byte numberOfLeadingZeros(final byte num) {
         }
         return result;
     }
+
+    /**
+     * Checks the buffer for its validity.
+     * @param buf The buffer
+     * @param bytes The bytes
+     * @param type The type to fit into
+     * @return The same buffer
+     */
+    private static ByteBuffer whenFit(final ByteBuffer buf, final byte[] bytes,
+        final Class<?> type) {
+        final int expected;
+        try {
+            expected = type.getField("BYTES").getInt(null);
+        } catch (final NoSuchFieldException | IllegalAccessException ex) {
+            throw new IllegalArgumentException(ex);
+        }
+        if (bytes.length != expected) {
+            throw new ExFailure(
+                String.format(
+                    "Can't convert %d bytes to %s, exactly %d bytes expected",
+                    bytes.length, type.getName(), expected
+                )
+            );
+        }
+        return buf;
+    }
 }

eo-runtime/src/main/java/org/eolang/Expect.java

@@ -0,0 +1,82 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016-2024 Objectionary.com
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.eolang;
+
+/**
+ * This wrapper helps us explain our expectations in an error
+ * message that we throw.
+ *
+ * @param <T> Type of returned value
+ * @since 0.41.0
+ */
+public final class Expect<T> {
+
+    /**
+     * The action.
+     */
+    private final Expect.Action<T> action;
+
+    /**
+     * The message.
+     */
+    private final String message;
+
+    /**
+     * Ctor.
+     * @param act The action
+     * @param msg Additional explanation
+     */
+    public Expect(final Expect.Action<T> act, final String msg) {
+        this.action = act;
+        this.message = msg;
+    }
+
+    /**
+     * Take the value from the lambda.
+     * @return The value
+     * @checkstyle MethodNameCheck (3 lines)
+     */
+    @SuppressWarnings("PMD.ShortMethodName")
+    public T it() {
+        try {
+            return this.action.exec();
+        } catch (final ExFailure ex) {
+            throw new ExFailure(this.message, ex);
+        }
+    }
+
+    /**
+     * The action.
+     * @param <T> The type
+     * @since 0.41.0
+     */
+    public interface Action<T> {
+        /**
+         * Run it.
+         * @return The value
+         */
+        T exec();
+    }
+}

eo-runtime/src/test/java/EOorg/EOeolang/EOnumber$EOtimesTest.java

@@ -0,0 +1,71 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016-2024 Objectionary.com
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/*
+ * @checkstyle PackageNameCheck (10 lines)
+ * @checkstyle TrailingCommentCheck (3 lines)
+ */
+package EOorg.EOeolang; // NOPMD
+
+import org.eolang.Attr;
+import org.eolang.Data;
+import org.eolang.Dataized;
+import org.eolang.PhWith;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test case for {@link EOnumber$EOtimes}.
+ *
+ * @since 0.41
+ * @checkstyle TypeNameCheck (3 lines)
+ */
+@SuppressWarnings("PMD.AvoidDollarSigns")
+final class EOnumber$EOtimesTest {
+
+    @Test
+    void throwsCorrectError() {
+        MatcherAssert.assertThat(
+            "the message in the error is correct",
+            Assertions.assertThrows(
+                EOerror.ExError.class,
+                () -> new Dataized(
+                    new PhWith(
+                        new PhWith(
+                            new EOnumber$EOtimes(),
+                            Attr.RHO,
+                            new Data.ToPhi(4L)
+                        ),
+                        "x",
+                        new Data.ToPhi(true)
+                    )
+                ).take(),
+                "multiplies 3 by TRUE and fails with a proper message that explains what happened"
+            ).getMessage(),
+            Matchers.containsString("number.times expects its second argument to be a number")
+        );
+    }
+}

eo-runtime/src/test/java/org/eolang/BytesOfTest.java

@@ -121,7 +121,7 @@ void checksAsNumberLong() {
     void checksUnderflowForLong() {
         final Bytes bytes = new BytesOf("A");
         Assertions.assertThrows(
-            UnsupportedOperationException.class,
+            ExFailure.class,
             bytes::asNumber,
             AtCompositeTest.TO_ADD_MESSAGE
         );