t1300: test "set all" mode with value-pattern

Without additional modifiers, 'git config <key> <value>' attempts
to set a single value in the .git/config file. When the
value-pattern parameter is supplied, this command behaves in a
non-trivial manner.

Consider 'git config <key> <value> <value-pattern>'. The expected
behavior is as follows:

1. If there are multiple existing values that match 'value-pattern',
   then the command fails. Users should use --replace-all instead.

2. If there is no existing values match 'value-pattern', then the
   'key=value' pair is appended, making this 'key' a multi-valued
   config setting.

3. If there is one existing value that matches 'value-pattern', then
   the new config has one entry where 'key=value'.

Add a test that demonstrates these options. Break from the existing
pattern in t1300-config.sh to use 'git config --file=<file>' instead of
modifying .git/config directly to prevent possibly incompatible repo
states. Also use 'git config --file=<file> --list' for config state
comparison instead of the config file format. This makes the tests
more readable.

Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: derrickstolee

t/t1300-config.sh

@@ -1917,4 +1917,43 @@ test_expect_success '--replace-all does not invent newlines' '
 	test_cmp expect .git/config
 '
 
+test_expect_success 'set all config with value-pattern' '
+	test_when_finished rm -f config initial &&
+	git config --file=initial abc.key one &&
+
+	# no match => add new entry
+	cp initial config &&
+	git config --file=config abc.key two a+ &&
+	git config --file=config --list >actual &&
+	cat >expect <<-\EOF &&
+	abc.key=one
+	abc.key=two
+	EOF
+	test_cmp expect actual &&
+
+	# multiple matches => failure
+	test_must_fail git config --file=config abc.key three o+ 2>err &&
+	test_i18ngrep "has multiple values" err &&
+
+	# multiple values, no match => add
+	git config --file=config abc.key three a+ &&
+	git config --file=config --list >actual &&
+	cat >expect <<-\EOF &&
+	abc.key=one
+	abc.key=two
+	abc.key=three
+	EOF
+	test_cmp expect actual &&
+
+	# single match => replace
+	git config --file=config abc.key four h+ &&
+	git config --file=config --list >actual &&
+	cat >expect <<-\EOF &&
+	abc.key=one
+	abc.key=two
+	abc.key=four
+	EOF
+	test_cmp expect actual
+'
+
 test_done