Add namespace-typo detector

This changeset adds a new lint detector which looks for typos in the
namespace declaration for Android. If it sees the prefix "android" it
ensures that the URI matches exactly (and case-sensitively)
   http://schemas.android.com/apk/res/android

If the prefix is "a", it also checks for the above prefix, but only
warns if the difference is "close" (edit distance <= 3) such that
it belives it's a typo, not some unrelated prefix bound to "a".

(This was requested in http://b.android.com/25449)

Change-Id: Ic6dee77a300fc048cb9bee3e455f533b858ef6bb

8 files changed, 261 insertions, 1 deletions

diff --git a/lint/libs/lint_api/src/com/android/tools/lint/client/api/XmlVisitor.java b/lint/libs/lint_api/src/com/android/tools/lint/client/api/XmlVisitor.java
index ec6bd6a..c76d44d 100644
--- a/lint/libs/lint_api/src/com/android/tools/lint/client/api/XmlVisitor.java
+++ b/lint/libs/lint_api/src/com/android/tools/lint/client/api/XmlVisitor.java
@@ -181,7 +181,11 @@ class XmlVisitor {
             NamedNodeMap attributes = element.getAttributes();
             for (int i = 0, n = attributes.getLength(); i < n; i++) {
                 Attr attribute = (Attr) attributes.item(i);
-                List<Detector.XmlScanner> list = mAttributeToCheck.get(attribute.getLocalName());
+                String name = attribute.getLocalName();
+                if (name == null) {
+                    name = attribute.getName();
+                }
+                List<Detector.XmlScanner> list = mAttributeToCheck.get(name);
                 if (list != null) {
                     for (int j = 0, max = list.size(); j < max; j++) {
                         Detector.XmlScanner check = list.get(j);
diff --git a/lint/libs/lint_checks/src/com/android/tools/lint/checks/BuiltinIssueRegistry.java b/lint/libs/lint_checks/src/com/android/tools/lint/checks/BuiltinIssueRegistry.java
index ed5586d..67aabdb 100644
--- a/lint/libs/lint_checks/src/com/android/tools/lint/checks/BuiltinIssueRegistry.java
+++ b/lint/libs/lint_checks/src/com/android/tools/lint/checks/BuiltinIssueRegistry.java
@@ -125,6 +125,7 @@ public class BuiltinIssueRegistry extends IssueRegistry {
         issues.add(ViewTypeDetector.ISSUE);
         issues.add(WrongImportDetector.ISSUE);
         issues.add(ViewConstructorDetector.ISSUE);
+        issues.add(TypoDetector.ISSUE);
         issues.add(AlwaysShowActionDetector.ISSUE);
 
         addCustomIssues(issues);
diff --git a/lint/libs/lint_checks/src/com/android/tools/lint/checks/TypoDetector.java b/lint/libs/lint_checks/src/com/android/tools/lint/checks/TypoDetector.java
new file mode 100644
index 0000000..3fcbcf5
--- /dev/null
+++ b/lint/libs/lint_checks/src/com/android/tools/lint/checks/TypoDetector.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.tools.lint.checks;
+
+import static com.android.tools.lint.detector.api.LintConstants.ANDROID_URI;
+
+import com.android.tools.lint.detector.api.Category;
+import com.android.tools.lint.detector.api.Issue;
+import com.android.tools.lint.detector.api.LintUtils;
+import com.android.tools.lint.detector.api.ResourceXmlDetector;
+import com.android.tools.lint.detector.api.Scope;
+import com.android.tools.lint.detector.api.Severity;
+import com.android.tools.lint.detector.api.Speed;
+import com.android.tools.lint.detector.api.XmlContext;
+
+import org.w3c.dom.Attr;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+/**
+ * Check which looks for likely typos in various places.
+ */
+public class TypoDetector extends ResourceXmlDetector {
+    private static final String XMLNS_ANDROID = "xmlns:android";    //$NON-NLS-1$
+    private static final String XMLNS_A = "xmlns:a";                //$NON-NLS-1$
+
+    /** The main issue discovered by this detector */
+    public static final Issue ISSUE = Issue.create(
+            "NamespaceTypo", //$NON-NLS-1$
+            "Looks for misspellings in namespace declarations",
+
+            "Accidental misspellings in namespace declarations can lead to some very " +
+            "obscure error messages. This check looks for potential misspellings to " +
+            "help track these down.",
+            Category.CORRECTNESS,
+            8,
+            Severity.WARNING,
+            TypoDetector.class,
+            Scope.RESOURCE_FILE_SCOPE);
+
+    /** Constructs a new {@link TypoDetector} */
+    public TypoDetector() {
+    }
+
+    @Override
+    public Speed getSpeed() {
+        return Speed.FAST;
+    }
+
+    @Override
+    public Collection<String> getApplicableAttributes() {
+        return Arrays.asList(XMLNS_ANDROID, XMLNS_A);
+    }
+
+    @Override
+    public void visitAttribute(XmlContext context, Attr attribute) {
+        String value = attribute.getValue();
+        if (!value.equals(ANDROID_URI)) {
+            if (attribute.getName().equals(XMLNS_A)) {
+                // For the "android" prefix we always assume that the namespace prefix
+                // should be our expected prefix, but for the "a" prefix we make sure
+                // that it's at least "close"; if you're bound it to something completely
+                // different, don't complain.
+                if (LintUtils.editDistance(ANDROID_URI, value) > 4) {
+                    return;
+                }
+            }
+
+            if (value.equalsIgnoreCase(ANDROID_URI)) {
+                context.report(ISSUE, attribute, context.getLocation(attribute),
+                        String.format("URI is case sensitive: was \"%1$s\", expected \"%2$s\"",
+                                value, ANDROID_URI), null);
+            } else {
+                context.report(ISSUE, attribute, context.getLocation(attribute),
+                        String.format("Unexpected namespace URI bound to the \"android\" " +
+                                "prefix, was %1$s, expected %2$s", value, ANDROID_URI), null);
+            }
+        }
+    }
+}
diff --git a/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/TypoDetectorTest.java b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/TypoDetectorTest.java
new file mode 100644
index 0000000..b9af7a2
--- /dev/null
+++ b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/TypoDetectorTest.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.tools.lint.checks;
+
+import com.android.tools.lint.detector.api.Detector;
+
+@SuppressWarnings("javadoc")
+public class TypoDetectorTest extends AbstractCheckTest {
+    @Override
+    protected Detector getDetector() {
+        return new TypoDetector();
+    }
+
+    public void test() throws Exception {
+        assertEquals(
+                "wrong_namespace.xml:2: Warning: Unexpected namespace URI bound to the " +
+                "\"android\" prefix, was http://schemas.android.com/apk/res/andriod, " +
+                "expected http://schemas.android.com/apk/res/android",
+
+                lintProject("res/layout/wrong_namespace.xml"));
+    }
+
+    public void test2() throws Exception {
+        assertEquals(
+                "wrong_namespace2.xml:2: Warning: URI is case sensitive: was " +
+                "\"http://schemas.android.com/apk/res/Android\", expected " +
+                "\"http://schemas.android.com/apk/res/android\"",
+
+                lintProject("res/layout/wrong_namespace2.xml"));
+    }
+
+    public void test3() throws Exception {
+        assertEquals(
+                "wrong_namespace3.xml:2: Warning: Unexpected namespace URI bound to the " +
+                "\"android\" prefix, was http://schemas.android.com/apk/res/androi, " +
+                "expected http://schemas.android.com/apk/res/android",
+
+                lintProject("res/layout/wrong_namespace3.xml"));
+    }
+
+    public void testOk() throws Exception {
+        assertEquals(
+                "No warnings.",
+
+                lintProject("res/layout/wrong_namespace4.xml"));
+    }
+}
diff --git a/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace.xml b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace.xml
new file mode 100644
index 0000000..c6e2143
--- /dev/null
+++ b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/andriod"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical" >
+
+    <include
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        layout="@layout/layout2" />
+
+    <Button
+        android:id="@+id/button1"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button" />
+
+    <Button
+        android:id="@+id/button2"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button" />
+
+</LinearLayout>
diff --git a/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace2.xml b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace2.xml
new file mode 100644
index 0000000..49dc611
--- /dev/null
+++ b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace2.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/Android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical" >
+
+    <include
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        layout="@layout/layout2" />
+
+    <Button
+        android:id="@+id/button1"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button" />
+
+    <Button
+        android:id="@+id/button2"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button" />
+
+</LinearLayout>
diff --git a/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace3.xml b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace3.xml
new file mode 100644
index 0000000..02252b4
--- /dev/null
+++ b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace3.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:a="http://schemas.android.com/apk/res/androi"
+    a:layout_width="match_parent"
+    a:layout_height="match_parent"
+    a:orientation="vertical" >
+
+    <include
+        a:layout_width="wrap_content"
+        a:layout_height="wrap_content"
+        layout="@layout/layout2" />
+
+    <Button
+        a:id="@+id/button1"
+        a:layout_width="wrap_content"
+        a:layout_height="wrap_content"
+        a:text="Button" />
+
+    <Button
+        a:id="@+id/button2"
+        a:layout_width="wrap_content"
+        a:layout_height="wrap_content"
+        a:text="Button" />
+
+</LinearLayout>
diff --git a/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace4.xml b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace4.xml
new file mode 100644
index 0000000..4142622
--- /dev/null
+++ b/lint/libs/lint_checks/tests/src/com/android/tools/lint/checks/data/res/layout/wrong_namespace4.xml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This file does *not* have a wrong namespace: it's testdata to make sure we don't complain when "a" is defined for something unrelated -->
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:a="http://something/very/different"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical" >
+
+    <include
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        layout="@layout/layout2" />
+
+    <Button
+        android:id="@+id/button1"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button" />
+
+    <Button
+        android:id="@+id/button2"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Button" />
+
+</LinearLayout>