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Avoid null pointer exceptions when calling getCapabilities #1094

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Merged
merged 1 commit into from
Feb 5, 2019
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Avoid null pointer exceptions when calling getCapabilities #1094

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3 changes: 2 additions & 1 deletion src/main/java/io/appium/java_client/DefaultGenericMobileDriver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -157,7 +157,8 @@ public List findElementsByXPath(String using) {

@Override
public String toString() {
Capabilities capabilities = getCapabilities();
return String.format("%s, Capabilities: %s", getClass().getCanonicalName(),
getCapabilities().asMap().toString());
capabilities != null ? capabilities.asMap().toString() : "null");
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I'd rather use checkNotNull macros everywhere

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or this is normal that getCapabilities can sometimes return null?

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@etanol etanol Jan 31, 2019 •
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getCapabilities will be null until the response of the new session request, where the real capabilities are returned by the server.

As I mentioned in the description, if the new session command fails (which can be pretty often when you are trying to set up the proper version combination of Appium, Automation and device), this NullPointerException masks the real failure (with no exception nesting).

So, overall, this makes the initial set up incredibly frustrating.

The idea of this change is to avoid NPEs altogether.

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@mykola-mokhnach mykola-mokhnach Jan 31, 2019 •
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yep, I've checked the Selenium code and it's how it currently works. Although I would like to get the response to SeleniumHQ/selenium#6903 first. What if this is just a bug and not the expected behaviour?

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I'm ok about learning the official posture. However, if RemoteWebDriver does indeed have a typo (missing a this.), then the exception masking would still remain. But instead of NullPointerException, a ClassCastException would be thrown:

java-client/src/main/java/io/appium/java_client/android/AndroidDriver.java

Line 210 in fa71401

MutableCapabilities capabilities = (MutableCapabilities) super.getCapabilities();

In such a case, the fix would be much uglier.

}
}
6 changes: 5 additions & 1 deletion src/main/java/io/appium/java_client/android/AndroidDriver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import javax.annotation.Nullable;

/**
* Android driver implementation.
Expand Down Expand Up @@ -206,9 +207,12 @@ public AndroidBatteryInfo getBatteryInfo() {
*
* @return given {@link Capabilities}
*/
@Nullable
public Capabilities getCapabilities() {
MutableCapabilities capabilities = (MutableCapabilities) super.getCapabilities();
capabilities.setCapability(PLATFORM_NAME, ANDROID_PLATFORM);
if (capabilities != null) {
capabilities.setCapability(PLATFORM_NAME, ANDROID_PLATFORM);
}
return capabilities;
}

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6 changes: 5 additions & 1 deletion src/main/java/io/appium/java_client/ios/IOSDriver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@
import java.time.Duration;
import java.util.Collections;
import java.util.Map;
import javax.annotation.Nullable;

/**
* iOS driver implementation.
Expand Down Expand Up @@ -207,9 +208,12 @@ private class InnerTargetLocator extends RemoteTargetLocator {
*
* @return given {@link Capabilities}
*/
@Nullable
public Capabilities getCapabilities() {
MutableCapabilities capabilities = (MutableCapabilities) super.getCapabilities();
capabilities.setCapability(PLATFORM_NAME, IOS_PLATFORM);
if (capabilities != null) {
capabilities.setCapability(PLATFORM_NAME, IOS_PLATFORM);
}
return capabilities;
}

Expand Down