Interpolation within array contantenation does not always work

[adamhonen]

Trying to load configuration from a file that has the following :

some_array = []
some_array += {
    replaced_a = ${replacement_a}
}
some_array += {
    replaced_b = ${replacement_b}
}

Where replacement_a & replacement_b are provided via another configuration object (I use configFromClasspath.resolveWith(anotherConfig, ConfigResolveOptions.defaults()))
I get com.typesafe.config.ConfigException$NotResolved: called unwrapped() on value with unresolved substitutions, need to Config#resolve() first, see API docs

But when I modify the configuration to:

workaround_a {
  name=${replacement_a}
  prop = "aaa"
}

workaround_b = {
  name=${replacement_b}
  prop = "bbb"
}

some_array = [${workaround_a},${workaround_b}]

It works fine.
Also I see no issues when parsing the configuration String directly.

[adamhonen]

Naming the first configuration as arrayInterpolation.conf and naming the second as arrayInterpolationWorkaround, I’ve written the following test that shows this:

import java.util.HashMap

import org.junit.Test

import com.typesafe.config.Config
import com.typesafe.config.ConfigFactory
import com.typesafe.config.ConfigParseOptions
import com.typesafe.config.ConfigResolveOptions

class ArrayInterpolationTest extends TestUtils {

    def getExternalConfig(): Config = {
        val base = new HashMap[String, String]()
        base.put("replacement_a", "a");
        base.put("replacement_b", "b");
        return ConfigFactory.parseMap(base)
    }

    @Test
    def interpolationWithinArrayConcatenation(): Unit = {
        val externalConfig = getExternalConfig()

        verifyFrom(externalConfig, "arrayInterpolation")
    }

    @Test
    def interpolationWithinArrayDefinition(): Unit = {
        val externalConfig = getExternalConfig()

        verifyFrom(externalConfig, "arrayInterpolationWorkaround")
    }

    def verifyFrom(externalConfig: Config, confFile: String): Unit = {
        val fromClasspath = ConfigFactory.load(confFile, ConfigParseOptions.defaults(), ConfigResolveOptions.defaults().setAllowUnresolved(true))
        val withSubstiturions = fromClasspath.resolveWith(externalConfig, ConfigResolveOptions.defaults())
        val config = externalConfig.withFallback(withSubstiturions).resolve()
    }
}

[havocp]

So there was a bug in toString of ConfigDelayedMerge, which created a misleading error message. I just fixed that on master. With that fixed, we get the correct error message and this turns out to be the same problem as #332 I believe.

[error] Test com.typesafe.config.impl.ArrayInterpolationTest.interpolationWithinArrayConcatenation failed: com.typesafe.config.ConfigException$BugOrBroken: replace in parent not possible ConfigDelayedMerge([],[{"replaced_a":${replacement_a}}],[],[{"replaced_a":${replacement_a}}][{"replaced_b":${replacement_b}}]) with ConfigDelayedMerge([],[{"replaced_a":${replacement_a}}]) in ResolveSource(root=SimpleConfigObject({"replacement_a":"a","replacement_b":"b"}), pathFromRoot=null), took 0.003 sec
[error]     at com.typesafe.config.impl.ResolveSource.replaceWithinCurrentParent(ResolveSource.java:245)
[error]     at com.typesafe.config.impl.ConfigDelayedMerge.resolveSubstitutions(ConfigDelayedMerge.java:110)
[error]     at com.typesafe.config.impl.ConfigDelayedMerge.resolveSubstitutions(ConfigDelayedMerge.java:59)
[error]     at com.typesafe.config.impl.ResolveContext.realResolve(ResolveContext.java:179)
[error]     at com.typesafe.config.impl.ResolveContext.resolve(ResolveContext.java:142)
[error]     at com.typesafe.config.impl.SimpleConfigObject$ResolveModifier.modifyChildMayThrow(SimpleConfigObject.java:379)
[error]     at com.typesafe.config.impl.SimpleConfigObject.modifyMayThrow(SimpleConfigObject.java:312)
[error]     at com.typesafe.config.impl.SimpleConfigObject.resolveSubstitutions(SimpleConfigObject.java:398)
[error]     at com.typesafe.config.impl.ResolveContext.realResolve(ResolveContext.java:179)
[error]     at com.typesafe.config.impl.ResolveContext.resolve(ResolveContext.java:142)
[error]     at com.typesafe.config.impl.ResolveContext.resolve(ResolveContext.java:231)
[error]     at com.typesafe.config.impl.SimpleConfig.resolveWith(SimpleConfig.java:74)
[error]     at com.typesafe.config.impl.SimpleConfig.resolveWith(SimpleConfig.java:37)
[error]     at com.typesafe.config.impl.ArrayInterpolationTest.verifyFrom(ArrayConcatTest.scala:35)
[error]     at com.typesafe.config.impl.ArrayInterpolationTest.interpolationWithinArrayConcatenation(ArrayConcatTest.scala:30)
[error]  
...

[havocp]

Here's a version of the test case without any external files:

    val replacements = ConfigFactory.parseString("""
  replacement_a = a
  replacement_b = b
""")

    val arrayInterpolation = """
  some_array = []
  some_array += {
    replaced_a = ${replacement_a}
  }
  some_array += {
    replaced_b = ${replacement_b}
  }
"""

    @Test
    def interpolationWithinArrayConcatenation(): Unit = {
        val fromClasspath = ConfigFactory.load(ConfigFactory.parseString(arrayInterpolation, ConfigParseOptions.defaults()), ConfigResolveOptions.defaults().setAllowUnresolved(true))
        val withSubstitutions = fromClasspath.resolveWith(replacements, ConfigResolveOptions.defaults())
        val config = replacements.withFallback(withSubstitutions).resolve()
    }